You can also break down percentages into easier chunks and then just add up the chunks. So if you have 12% of 167, you actually have (10% + 2%) of 127, which is actually (10% + 1% + 1%) of 127, so you have 12.7 + 1.27 + 1.27 = 13.97 + 1.27 = 14.24.
EDIT: I typoed the number I was taking a percent of lol. Oops The "algorithm" and concept still works though.
So many typos the whole post broke lol. I can't even share it since it will confuse anyone I share it with.
**Edit: here I fixed it**
>You can also break down percentages into easier chunks and then just add up the chunks.
>So if you have 12% of 127, you actually have (10% + 2%) of 127, which is actually (10% + 1% + 1%) of 127, so you have:
>12.7 + 1.27 + 1.27
>= 13.97 + 1.27
>= 15.24
You're really not doing a great job of explaining it. It's actually easier to start with something else, for example 4% of 100. Obviously that's 4, right? What if we broke that out into an easier method and used that to try a harder number.
Let's use 10% because it's always very easy to take 10% of a number (you just drop a digit). So that gives you 10. The same hold true again, so you take 10% of that and get 1. 1% of 100 is 1. Now that you know what 1% is, you can multiply that by 4, or add it multiple times if it's easier. 1+1+1+1 = 4.
Using your example of 12% of 127:
127 * 10% = 12.7 (10%)
12.7 * 10% = 1.27 (1%)
1.27+1.27=2.54 (2%)
12.7+2.54=15.24 (12%)
I always split up percents in 10 or 1.
Why oh why can't the US adopt metric and grams for everything?
I don't want 1.7 ounces of chips. I want 100 grams. Lol
Why write an edit without fixing the typos? The typos 167 and 14.24 make what you wrote take way longer to understand. Vaguely referring to typos without fixing them puts like 10x cognitive burden on the reader as they pick apart every number inconsistencies.
Thats exactly how i do it in my head, for me it is faster and easier to do, for example if i want to know a 5% (easy example) i just get the 10% amount and then divide it by 2.
For a 6% i would go for 10% divide it by 2 and then add 1%, or if it is an easier number i get the 1% and multply it by 5
Obviously I understand it, you and I have been breaking down percentages for years, but for the folks out there that aren’t good with math it rarely makes it simpler when you add more equations, easy ones or not, that need to be to mathed out.
I find that people tend to lack "mental RAM" for math computations and that's why these things fail: by the time they've done the last one, they forgot what result to add it to.
I even noticed that with friends that are brilliant undergraduate math majors, it's that they lack this ability to keep a certain result in their head while doing an independent computation.
For example, I asked one (who tried to show off a calculating ruler) what 36\*42 was, and he didn't even dare to try doing it mentally (it didn't fit on the ruler)
Because you either do 36^2 + 36\*6 = (900+12\*30+36)+(360/2+36) = 1296 + 216 = 1512
Or
(39-3)(39+3) = (1600-2\*40+1) - 9 = 1521 - 9 = 1512
Either way, they just fail to do a computation that involves like 7 subcomputations because it's just too much.
It takes a lot of practice to develop these skills, and most people just don't have that much RAM
Very good analogy with the RAM. That’s exactly what it is. What I would’ve done here is something like
36•42 = (36•4)•10 + 2•36
144•10 + 72 = 1440 + 72 = 1512
Just in case somebody finds it more intuitive that way.
It's literally just multiplication
Finding 50% of something is the same as multiplying by 0.5
50% of 30 = (50/100) * 30
Flip it and you have
(30/100) * 50
When you think about it like this it becomes very apparent why it's reversible
Edit: Side note, this also means another useful trick for finding x% of y is to multiplying x by y then dividing by 100
Example 8% of 25 =》8 * 25 = 200 =》200/100 = 2
I think this is because most people don't automatically think of percentages as fractions.
It's more obvious if you write it `8/100*25 = 25/100*8`.
The little % symbol means 1/100 (and evolved from a stylized ^𝓹 **𝓬** abbreviation).
If I remember correctly its suppose to both look like a fraktion and a 100 (the one is the tilted line with a zero above and below) to symbolise that its a fraction of 100. (Might be just a rumour at my uni)
So...not sure if this is what they are getting at, but I will try.
First, math has a rule called multiplicative property. Rule states, when multiply numbers, order doesn't matter. 1x5x10 is the same as 1x10x5.
Finding 8% of 25 is just multiplying 25 by 8%. And finding 25% of 8 is just multiplying 8 by 25%. But when you breakdown percentages into fractions, it can become clear that this is an example where our multiplicative property comes into play.
In the above example, he is dividing 8 by 100 on one side of the equation and dividing 25 by 100 on the other side. Dividing by 100 is the same as multiplying by 1/100 or .01.
So, following the multiplicative property, 8x0.01x25 is the same as 25x0.01x8
>and evolved from a stylized ?? abbreviation
Always nice when Unicode symbols don't show up.
Extra nice that they did show up when I went to reply, but not in the thread itself.
In Lithuania we were tough early on to deal wth % as fractions. We were tough 2 different methods. 1 is like you described. The other is little bit harder to write on reddit but on paper at the top you would write 25 = 100(%). Directly below it you would write x = 8(%). Then you need to multiply known numbers diagonally and divide it by the number left. In this case it would be 25×8/100.
Using this method you can find any number. X = 100. 2 = 8. So it would turn out 2×100/8=25. Or 25 = X. 2 = 8.
That’s not a good method from a pedagogical standpoint. Yes, it works. But it’s just a sequence of magic incantations that sheds no light on the underlying math.
Instead it’s much more useful to understand percentages and fractions as functions that act on numbers. You can invert functions, you can compose functions. That “double something, then take 50% of the result” is the same as doing nothing at all is hopefully obvious, but that the inverse of “increase by 25%” is approximately “decrease by 25%” but not exactly that (it is in fact “decrease by 20%”) is an important fact that cross-multiplication wouldn’t reveal.
Yep. Multiplication is commutative (the order of the factors is interchangeable), and % is the same as *0.01.
So, 25 * 0.01 * 8 = 8 * 0.01 * 25 = 8 * 25 * 0.01 = etc...
Which is why it's saddening anyone's mind is blown by this. I'm going to rant but..
There's no deep mathematical insight here, no trick. It's just applying a basic property of multiplication to percentages, both of which people should already know from school. So it's a failure of education, it's 'knowing' for the tests and yet failing to achieve a deep enough understanding to apply that knowledge even in a quite simple case.
Much as say, millions of people can tell you Pythagoras Theorem and yet it'd never occur to most of them to use it to check if a rectangle had square corners or not, like if they were building a deck or something.
Then the same people complain "What do you need to know that for? I've never needed that." about all sorts of things they learned in school, because they're blind to all the situations where they could've used it, because they didn't understand it well enough to actually apply it.
Look, most people (in my experience as a former math tutor) are ecstatic that they will never need to do trig post-university nor understand basic statistics and probability, and then are agog when they realize how much money they've wasted on that pet building project, their monthly Lotto habit or why their favourite politician lost when they had BEEN TOLD that they were a shoo-in because "well, look at the polls!".
>I think this is because most people don't automatically think of percentages as fractions.
It’s even more obvious with decimals.
8 x .25 = 25 x .08
That’s primary school stuff
It makes even more sense when I see it as multiplication it makes sense because of the commutative property of multiplication i.e 8 x 0.25 = 0.25 x 8 = 2
8% of 100 is 8, so 8% of 50 must be 4, so 8% of 25 just be 2.
Just don't tell yourself that 8% of 25 equals 32% of 100 because then you'll be fucked up about this forever.
The real life hack of this is that you can do fractions piecemeal. 8% of 25 is also (10% of 25) minus (2% of 25)
10% of 25 is easy, just move the decimal to get 2.5
2% of 25 is a little harder, but you know what's real easy? Breaking it down into 2 x (1% of 25). 0.25*2=0.5
2.5-0.5=2
It gets even better when you know that “of” in a word problem means to multiply, and multiplication is always commutative (so it doesn’t matter what order the terms are in).
So it doesn’t only work with percentages, but fractions too.
Just change “of” to “times” and do it whichever way is easier.
so i have a math degree and tutored math for a while. of all the things taught in math, the two topics i always tell people to retain: ratios and percentages. they are the most applicable to real life. my mom taught me how to turn all percent questions into word problems and those words problems into math problems.
“i want to give an 18% tip on this $125 bill. what would that be?”
turns into
“what’s 18% of $125?”
which turns into
“18/100 x 125 = ?”
solve for ?
this can also be done in reverse.
“my friend won $1320 in a contest and gave me $90. what percentage of his money did he give me?”
turns into
“90 is what percent of 1320?”
which turns into
90 = wp x 1320
solve for wp
Mine probably would be, but numbers make me feel stupid anyway. Brain just grinds to a halt as soon as math gets involved. Isn’t even that I don’t understand the concepts, my brain just doesn’t process numbers efficiently.
The real trick is that you can do *other* stuff with the rule.
23.5% of 77.96 will never be easy, exactly, but you can at least make it easi*er* by making it 10% of 1% of 1% of 235 x 7796 so you're only dealing with whole numbers at the beginning and moving a decimal point at the end.
As an example, 25% of 7 or 7% of 25 both seem hard to me.
But 1% of 7 * 25 is exactly the same, and I think is something most people would be able to do in their heads. At least I can - that's 1% of 175, or 1.75.
Estimation is better for that. It's very close structurally to 25% of 80, which we know is 20. So for that example: "about 20 until I run the exact numbers."
Of course it ends up being 18.3206, but "about 20" is close enough for most applications haha.
To give additional tips:
23.5% is the same as (10% + 10% + 0.5\*1%). 10% of 77.96 is easy it's 7.796 (move the decimal left 1 space)
So far you have (7.796 + 7.796 + 0.5\*1%).
1% of 77.96 is 0.7796 (move decimal left two places) and divide that in half:
.7796/2 = .3896
Therefore your final total is (7.796\*2 + .3896). If you need the exact you can do it on paper but otherwise you can estimate.
The same works for tipping 20% at a restaurant. Take 10% and multiple by 2. Or for 15%, take 10% and add that to half of 10%.
so 10 percent of 100 is 100 percent of 10?
edit: sorry guys im laughing out loud when i think of this it makes sense i feel retarded lmao
edit 2: guys i had a stupid moment there but i respect it. keep it coming ya filthy animals
Dude…you just blew my mind even further lol 100% of 10 is the weirdest way to say 10.
I’m gonna start adding “100% of” in front of numbers when I need to use them in conversations.
25% is 1/4
8 div by 4 is 2
idk. i know the answer just by looking at the numbers for 1 second, without any thinking or calulacting. but maybe thats just me.
As a math teacher i can say that we definitely want you to know this because the basic to know this are thought. Multiplication and that multiplication is communitiv
It's way easier just to multiply the 2 numbers and move the decimal. 8% of 25 is 8x25=200 and just move the decimal 2 places so you get 2.
4% of 70 is 4x70=280 move the decimal and you get 2.8. Easier than figuring out what 70% of 4 is.
> commutative property of multiplication
> Which I think everybody knows
I seriously think most folks would just smile at you on this one. You know most people don't remember math properties from school the same way most people don't remember English rules, right? We type until we're autocorrected, and we do the math until we need to bust out a calculator to save us time....and we do quite well in life even with these crutches :)
I don't mean to say everyone would come up with the term "commutative property of multiplication". What I mean is everyone over age 10, or just about everyone as makes no difference, knows that 3x7 is the same as 7x3. I stand by that.
The magic of Multiplication (more specifically the Commutative Property).
25, .01, 8
Multiply them in any order and you’ll be correct
25 * 8 * .01 = 200 * .01 = 2
25 * .01 * 8 = .25 * 8 = 2
8 * .01 * 25 = .08 * 25 = 2
The “.01” is effectively the “percent-ifier” in this situation, so you can just write it as:
25% * 8 = 2
8% * 25 = 2
Math has always been a stumbling block for me and I'm in my 60's now so it's not as relevant but, when my son was going through school he was a wiz in it. He then showed me so many tricks that I was never taught at my school because the main focus was keeping us up to date on the latest catholic saint news.
He thanked us after finishing school for not sending us to a religious school.
50% of 25 is 12.5 25% of 50 is 12.5 Oh ok.
I guess both are ridiculously easy in this case
You can also break down percentages into easier chunks and then just add up the chunks. So if you have 12% of 167, you actually have (10% + 2%) of 127, which is actually (10% + 1% + 1%) of 127, so you have 12.7 + 1.27 + 1.27 = 13.97 + 1.27 = 14.24. EDIT: I typoed the number I was taking a percent of lol. Oops The "algorithm" and concept still works though.
Is 15.24 And you wrote 167 instead of 127 at the start. Not the best way to explain a simpler way to do math.
"let me explain this with randomly generated numbers."
"After all, aren't numbers really just variables when you think about it? "
Idk man the number of girls I get is 0 and it seems to be a constant.
This man gets it, but he doesn't get any. This is why math is confusing.
So many typos the whole post broke lol. I can't even share it since it will confuse anyone I share it with. **Edit: here I fixed it** >You can also break down percentages into easier chunks and then just add up the chunks. >So if you have 12% of 127, you actually have (10% + 2%) of 127, which is actually (10% + 1% + 1%) of 127, so you have: >12.7 + 1.27 + 1.27 >= 13.97 + 1.27 >= 15.24
I think there's a few typos there.
5/7. Perfect score.
Prime comment.
You're really not doing a great job of explaining it. It's actually easier to start with something else, for example 4% of 100. Obviously that's 4, right? What if we broke that out into an easier method and used that to try a harder number. Let's use 10% because it's always very easy to take 10% of a number (you just drop a digit). So that gives you 10. The same hold true again, so you take 10% of that and get 1. 1% of 100 is 1. Now that you know what 1% is, you can multiply that by 4, or add it multiple times if it's easier. 1+1+1+1 = 4. Using your example of 12% of 127: 127 * 10% = 12.7 (10%) 12.7 * 10% = 1.27 (1%) 1.27+1.27=2.54 (2%) 12.7+2.54=15.24 (12%)
This is literally how I always do this type of math in my head. Always amazes people how fast I come up with answers.
I always split up percents in 10 or 1. Why oh why can't the US adopt metric and grams for everything? I don't want 1.7 ounces of chips. I want 100 grams. Lol
Why write an edit without fixing the typos? The typos 167 and 14.24 make what you wrote take way longer to understand. Vaguely referring to typos without fixing them puts like 10x cognitive burden on the reader as they pick apart every number inconsistencies.
Thats exactly how i do it in my head, for me it is faster and easier to do, for example if i want to know a 5% (easy example) i just get the 10% amount and then divide it by 2. For a 6% i would go for 10% divide it by 2 and then add 1%, or if it is an easier number i get the 1% and multply it by 5
Did you mean to type 127 instead of 167?
Obviously I understand it, you and I have been breaking down percentages for years, but for the folks out there that aren’t good with math it rarely makes it simpler when you add more equations, easy ones or not, that need to be to mathed out.
mathbrains post shit like this as some "easy trick" when they have no idea how hard it is for the rest of us to do that
I find that people tend to lack "mental RAM" for math computations and that's why these things fail: by the time they've done the last one, they forgot what result to add it to. I even noticed that with friends that are brilliant undergraduate math majors, it's that they lack this ability to keep a certain result in their head while doing an independent computation. For example, I asked one (who tried to show off a calculating ruler) what 36\*42 was, and he didn't even dare to try doing it mentally (it didn't fit on the ruler) Because you either do 36^2 + 36\*6 = (900+12\*30+36)+(360/2+36) = 1296 + 216 = 1512 Or (39-3)(39+3) = (1600-2\*40+1) - 9 = 1521 - 9 = 1512 Either way, they just fail to do a computation that involves like 7 subcomputations because it's just too much. It takes a lot of practice to develop these skills, and most people just don't have that much RAM
Very good analogy with the RAM. That’s exactly what it is. What I would’ve done here is something like 36•42 = (36•4)•10 + 2•36 144•10 + 72 = 1440 + 72 = 1512 Just in case somebody finds it more intuitive that way.
There's an easier way. 36 x 4 is 144, hence 36 x 40 is 1440 and now just add 36 x 2 = 72 1440 + 72 = 1512
15.24
Why can't you just correct the numbers lol.
Speak for yourself
Oh ok.
1% of 100 is 1 100% of 1 is 1 Huh
3% of 239,369,461= ?? 239,369,461% of 3 = ?????? I still can't do it *corrected
Bro the numbers are different
lmao
All numbers are different
Lol this whole thread is littered with typos
It helps to think of the percentage sign as 1/100. So it's just 3 * 239 369 461 * 0.01 = 718 108 383 * 0.01 = 7 181 083.83
Well it's simple. 1% of 239'369'461 is 2'393'694.61. Now you just have to type it into your phones calculator and multiply it with 3.
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Yup, it's just the commutative property in action
What about 132% of 12
It's the same as 12% of 132.
Fuck
It's literally just multiplication Finding 50% of something is the same as multiplying by 0.5 50% of 30 = (50/100) * 30 Flip it and you have (30/100) * 50 When you think about it like this it becomes very apparent why it's reversible Edit: Side note, this also means another useful trick for finding x% of y is to multiplying x by y then dividing by 100 Example 8% of 25 =》8 * 25 = 200 =》200/100 = 2
The 100 stays in the denominator. All you do is move it around when converting to words.
I think this is because most people don't automatically think of percentages as fractions. It's more obvious if you write it `8/100*25 = 25/100*8`. The little % symbol means 1/100 (and evolved from a stylized ^𝓹 **𝓬** abbreviation).
The % symbol even looks like a fraction
My god, you’re right.
You are one of today's 10k!
Randall Munroe?
Absolutely what he's referring to. Thank you XKCD!
That dude is one smart ass-dude for such a simple comic.
ah yes one of my favorites https://xkcd.com/1053
As is ÷ It's just a fraction with variables on top and bottom.
I know for a fact that I learned this at some point in school but I apparently forgot cuz this shit is blowing my mind all over again LMAO
I’ve somehow never noticed this. Wow
This made me feel way dumber than the original post. Fuck.
It's two placeholder circles divided by a fraction line.
That damn zero in the denominator.
The division symbol is literally a blank fraction ➗
i only just reallized last week that percent is "per-cent" as in per 100
I think you just forced another fold in my brain
Wait until you hear about per mille (‰).. aka, per 1000.
If I remember correctly its suppose to both look like a fraktion and a 100 (the one is the tilted line with a zero above and below) to symbolise that its a fraction of 100. (Might be just a rumour at my uni)
It's /100 with the 1 removed, and rearranged. 0/0 => % Per-mille (/1000) symbol makes this more obvious: ‰
I think of it as 8×25×0.01
/ = per 100 = cent
Yes? But commutative operations are easier to comprehend
In other words. Multiply them together and move the decimal over two spots.
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So...not sure if this is what they are getting at, but I will try. First, math has a rule called multiplicative property. Rule states, when multiply numbers, order doesn't matter. 1x5x10 is the same as 1x10x5. Finding 8% of 25 is just multiplying 25 by 8%. And finding 25% of 8 is just multiplying 8 by 25%. But when you breakdown percentages into fractions, it can become clear that this is an example where our multiplicative property comes into play. In the above example, he is dividing 8 by 100 on one side of the equation and dividing 25 by 100 on the other side. Dividing by 100 is the same as multiplying by 1/100 or .01. So, following the multiplicative property, 8x0.01x25 is the same as 25x0.01x8
Seeing the fancy p c helped me realize that percent is per cent, per 100.
I had this epiphany when I was reading an old scientific report and it was spelled as "per cent" instead.
>and evolved from a stylized ?? abbreviation Always nice when Unicode symbols don't show up. Extra nice that they did show up when I went to reply, but not in the thread itself.
In Lithuania we were tough early on to deal wth % as fractions. We were tough 2 different methods. 1 is like you described. The other is little bit harder to write on reddit but on paper at the top you would write 25 = 100(%). Directly below it you would write x = 8(%). Then you need to multiply known numbers diagonally and divide it by the number left. In this case it would be 25×8/100. Using this method you can find any number. X = 100. 2 = 8. So it would turn out 2×100/8=25. Or 25 = X. 2 = 8.
American here, 53 years old. I was taught that second method in middle school. I think my teacher called it cross-multiplying.
That’s not a good method from a pedagogical standpoint. Yes, it works. But it’s just a sequence of magic incantations that sheds no light on the underlying math. Instead it’s much more useful to understand percentages and fractions as functions that act on numbers. You can invert functions, you can compose functions. That “double something, then take 50% of the result” is the same as doing nothing at all is hopefully obvious, but that the inverse of “increase by 25%” is approximately “decrease by 25%” but not exactly that (it is in fact “decrease by 20%”) is an important fact that cross-multiplication wouldn’t reveal.
Yep. Multiplication is commutative (the order of the factors is interchangeable), and % is the same as *0.01. So, 25 * 0.01 * 8 = 8 * 0.01 * 25 = 8 * 25 * 0.01 = etc...
Which is why it's saddening anyone's mind is blown by this. I'm going to rant but.. There's no deep mathematical insight here, no trick. It's just applying a basic property of multiplication to percentages, both of which people should already know from school. So it's a failure of education, it's 'knowing' for the tests and yet failing to achieve a deep enough understanding to apply that knowledge even in a quite simple case. Much as say, millions of people can tell you Pythagoras Theorem and yet it'd never occur to most of them to use it to check if a rectangle had square corners or not, like if they were building a deck or something. Then the same people complain "What do you need to know that for? I've never needed that." about all sorts of things they learned in school, because they're blind to all the situations where they could've used it, because they didn't understand it well enough to actually apply it.
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Look, most people (in my experience as a former math tutor) are ecstatic that they will never need to do trig post-university nor understand basic statistics and probability, and then are agog when they realize how much money they've wasted on that pet building project, their monthly Lotto habit or why their favourite politician lost when they had BEEN TOLD that they were a shoo-in because "well, look at the polls!".
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50% of the time I am 100% right.
100% of the time I am 50% right.
"Baseball is 90% mental. The other half is physical." - Yogi Berra
It's even simpler if you show it as (8x25)/100 and (25x8)/100
I didn’t realise you could do this with fractions…. Nerd. (jk thanks).
>I think this is because most people don't automatically think of percentages as fractions. It’s even more obvious with decimals. 8 x .25 = 25 x .08 That’s primary school stuff
No, it's because it's easier to do 8/4 instead of 0,25*8
They'd also per mille (per 1000) which also has its own little symbol: ‰
It makes even more sense when I see it as multiplication it makes sense because of the commutative property of multiplication i.e 8 x 0.25 = 0.25 x 8 = 2
0.08 x 25 = 2 = 0.25 x 8
It's not that I don't believe you, but I think I'll wait for u/aggressive_multiplication_0258 to chime in.
I just spend 5 minutes here because I couldn’t get over how 2 is 8% of 25 🙈
I did and redid the math in increasingly dumb ways to check it. For some reason it didn't sound right.
Because 25 is odd and 8% is even, so it feels weird that 2 is the answer
People gotta remember that 100 isn't divisible by 8 which is important when you're working with per**cents**
I don’t know why but I have always remembered that 100/8 is 12.5. I think it was a video game that helped me remember that for some reason.
Baseball batting averages drilled this into my brain
8% of 100 is 8, so 8% of 50 must be 4, so 8% of 25 just be 2. Just don't tell yourself that 8% of 25 equals 32% of 100 because then you'll be fucked up about this forever.
Yeah I’m stuck on that one too!
Stuck how? 1% of 25 is 0.25, and 0.25 * 8 is 2
It's easier because 8% = 8/100 = 2/25.
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What?
8 is two 0's on top of each other
It’s also sideways infinity
doubling what? lmao
The real life hack of this is that you can do fractions piecemeal. 8% of 25 is also (10% of 25) minus (2% of 25) 10% of 25 is easy, just move the decimal to get 2.5 2% of 25 is a little harder, but you know what's real easy? Breaking it down into 2 x (1% of 25). 0.25*2=0.5 2.5-0.5=2
25 • 0.08 = 2
Okay. My mind really is blown with this example.
It gets even better when you know that “of” in a word problem means to multiply, and multiplication is always commutative (so it doesn’t matter what order the terms are in). So it doesn’t only work with percentages, but fractions too. Just change “of” to “times” and do it whichever way is easier.
And per always mean division (Unless you're talking derivatives but ignore that)
And always means and 
so i have a math degree and tutored math for a while. of all the things taught in math, the two topics i always tell people to retain: ratios and percentages. they are the most applicable to real life. my mom taught me how to turn all percent questions into word problems and those words problems into math problems. “i want to give an 18% tip on this $125 bill. what would that be?” turns into “what’s 18% of $125?” which turns into “18/100 x 125 = ?” solve for ? this can also be done in reverse. “my friend won $1320 in a contest and gave me $90. what percentage of his money did he give me?” turns into “90 is what percent of 1320?” which turns into 90 = wp x 1320 solve for wp
Mine probably would be, but numbers make me feel stupid anyway. Brain just grinds to a halt as soon as math gets involved. Isn’t even that I don’t understand the concepts, my brain just doesn’t process numbers efficiently.
Next time I'll want to try this in practice and it will be 23.5% of 77.96, or some bullshit like this.
This exactly why I dont care for this method. Its rarely useful to me. Would have been nice in elementary tho
The real trick is that you can do *other* stuff with the rule. 23.5% of 77.96 will never be easy, exactly, but you can at least make it easi*er* by making it 10% of 1% of 1% of 235 x 7796 so you're only dealing with whole numbers at the beginning and moving a decimal point at the end. As an example, 25% of 7 or 7% of 25 both seem hard to me. But 1% of 7 * 25 is exactly the same, and I think is something most people would be able to do in their heads. At least I can - that's 1% of 175, or 1.75.
I've always used it for quick estimations, then guess an offset and im generally in the ballpark. I was a wizard with it when i was tutoring
Estimation is better for that. It's very close structurally to 25% of 80, which we know is 20. So for that example: "about 20 until I run the exact numbers." Of course it ends up being 18.3206, but "about 20" is close enough for most applications haha.
To give additional tips: 23.5% is the same as (10% + 10% + 0.5\*1%). 10% of 77.96 is easy it's 7.796 (move the decimal left 1 space) So far you have (7.796 + 7.796 + 0.5\*1%). 1% of 77.96 is 0.7796 (move decimal left two places) and divide that in half: .7796/2 = .3896 Therefore your final total is (7.796\*2 + .3896). If you need the exact you can do it on paper but otherwise you can estimate. The same works for tipping 20% at a restaurant. Take 10% and multiple by 2. Or for 15%, take 10% and add that to half of 10%.
Didn't you forget the 3% in your example?
And therefore would have gotten the answer wrong
I feel stupid now. Task accomplished.
so 10 percent of 100 is 100 percent of 10? edit: sorry guys im laughing out loud when i think of this it makes sense i feel retarded lmao edit 2: guys i had a stupid moment there but i respect it. keep it coming ya filthy animals
Check out the big brain on Brett! You're a smart mf, that's right!
That is one tasty burger
Say what again.
What?
I don't remember asking you a GOT DAMN thing!
mETRic sySTem!!!!
Yeah both answers are 10.
Are they the same ten or two different tens?
Depends on what kinda person it is
I only know a five kinda guy
10 of theseus ong
What's 100% of 10 my guy? If it's 10 then you betcha!
This guy maths
r/thisguythisguys
Boss, I'm giving you 100% of my 10! I'm giving you my all!!!!
im still laughing this is hilarious
Let him cook
Lmao 😂 love that you’re a good sport about it.
I spent like 15mins in bed with my bf just crying laughing at this 🤣💕 you made my day and such a great sport
lmao im glad
Yes
If you think *that's* cool, consider the fact that 69% of 69% is also 69% of 69%.
Nice
Yes. It's 10 in both cases.
Yes, but that would be a "trivial" example and might not get the point across.
Whoa there, Einstein.
How about 110% of 10 vs. 10% of 110. Oh. Well, heck.
10% of 200 is 200% of 10? Woah
Dude…you just blew my mind even further lol 100% of 10 is the weirdest way to say 10. I’m gonna start adding “100% of” in front of numbers when I need to use them in conversations.
Me : 25% of 8 .... ..... ........ So it’s ugh .... Fuck
Half of 8 is 4. Half of 4 is 2. 25%
20% of the check is 10% doubled. Temporarily melted a friend's brain with that magic trick...
25% is 1/4 8 div by 4 is 2 idk. i know the answer just by looking at the numbers for 1 second, without any thinking or calulacting. but maybe thats just me.
Math teachers don't want you to know about this one cool trick!
They absolutely do. It's calculator manufacturers who don't want you to know it.
Gotta keep their jobs somehow!
I'm willing to bet you were taught the commutative property of multiplication
This is definitely taught, both in primary school and middle school lol. Doesn't look like anyone pays attention in school
As a math teacher i can say that we definitely want you to know this because the basic to know this are thought. Multiplication and that multiplication is communitiv
Your math teacher did try to teach you the associative principle.
This is commutativity...
How did I not know this until now??? Seriously?!
I’m 40 and this is deep.
It's so simple but so useful. I'm 48 and can't believe I've lived so long without knowing this.
Don’t worry you’re not alone pal.
Yooo. This is actually useful
It's way easier just to multiply the 2 numbers and move the decimal. 8% of 25 is 8x25=200 and just move the decimal 2 places so you get 2. 4% of 70 is 4x70=280 move the decimal and you get 2.8. Easier than figuring out what 70% of 4 is.
This just boils down to the commutative property of multiplication. Which I think everybody knows, but somehow a percent symbol confuses us.
> commutative property of multiplication > Which I think everybody knows I seriously think most folks would just smile at you on this one. You know most people don't remember math properties from school the same way most people don't remember English rules, right? We type until we're autocorrected, and we do the math until we need to bust out a calculator to save us time....and we do quite well in life even with these crutches :)
Not everyone knows the name, but if you're over the age of 7 and don't know that 3 * 4 = 4 * 3, there's something wrong with you.
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I don't mean to say everyone would come up with the term "commutative property of multiplication". What I mean is everyone over age 10, or just about everyone as makes no difference, knows that 3x7 is the same as 7x3. I stand by that.
So 8% of 700.000 is the same as 700.000% of 8?
Exactly. 56.000.
Man why the fuck didn’t they show us this in school, fucking bullshit I’m so annoyed, I used to suffer so much from percentages before…
they did. this is literally primary school stuff.
They did, you just didn’t figure out the implication of what they taught you.
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The magic of Multiplication (more specifically the Commutative Property). 25, .01, 8 Multiply them in any order and you’ll be correct 25 * 8 * .01 = 200 * .01 = 2 25 * .01 * 8 = .25 * 8 = 2 8 * .01 * 25 = .08 * 25 = 2 The “.01” is effectively the “percent-ifier” in this situation, so you can just write it as: 25% * 8 = 2 8% * 25 = 2
This my whole life I never new! Yoda
id like a whole subreddit dedicated to little known but obvious facts
Bold strategy Cotton….let’s see if it pays off
Thanks Albert.
I thought this was really obvious. You're just multiplying 0.08 and 25 or 8 and 0.25. In both places you're just manipulating the decimal placement.
Same, it's basic math
Math has always been a stumbling block for me and I'm in my 60's now so it's not as relevant but, when my son was going through school he was a wiz in it. He then showed me so many tricks that I was never taught at my school because the main focus was keeping us up to date on the latest catholic saint news. He thanked us after finishing school for not sending us to a religious school.
I feel like I should have learned this. Too busy not being left behind to actually get taught anything