Most of the people explaining this still make it more complicated than it needs to be, imo.
I just think the symbol “%” algebraically means 0.01
6/100 * 50 = 50/100 * 6
6 * 1/100 * 50 = 50 * 1/100 * 6
it all equals 3
Surprised how many people don’t know this. I suspect it is because people forget that percent literally means per 100 or /100 and the of is standing in for multiplication. So 6% of 50 is 6/100 * 50 or 6 * 50 * 1/100
I have been looked at like a wizard saying “oh that’s just the amount times 1.2”
commutable…
Yeah, now calculate 6% of 36
Edit: Replies itt make me believe that everyone on Lemmy is a chatbot
I usualy get the value of 1% and then multiple that back to original, so:
1% of 36 is 0.36 (just move 2 spaces) and thats times 6 which is 2.16
1% of 36 is .36, and .36 * 6 = 2.16. I’m a fan of this method most of the time, though the one in the OP is good for some math problems.
Bout tree fiddy
6% of 36 is 0.06 * 6². 6³ = 216 so 2.16
36% of 6 is roughly 33.(3)% of 6 which is 2.
3% of 6 is .18 so about 2.183.6/2+0.36 = 2.16
(10% of 36 halved, so 5%, plus 1% of 36)
My dyscalculic ass trying to remember what 50% of 6 is
Probably 5 tbh
is tree fiddy
6*50/100 = 50*6/100 if anyone is curious why this works.
Or, more generally:
Taking X percent of something is the same as multiplying by X/100.
X percent of Y = Y(X/100)=(YX)/100
Y percent of X = X(Y/100)=(XY)/100
(YX)/100=(XY)/100
Percentages are indeed reversible.
Huh. Learning a fun and cool math trick was not on the list of expected outcomes for today, but I’ll take it!
For those who want to dive deeper into the lake and the wisdom of the panzer: https://en.m.wikipedia.org/wiki/Commutative_property
Yes, 47% of 47 is certainly much easier to determine when you look at it as 47% of 47! Genius!
You can also
Multiply one side, divide the other to get the base number to get the base number to 100.
6% of 50 == 3% of 100 == 3
5% of 20 == 1% of 100 == 1
7% of 50 == 3.5℅ of 100 == 3.5
14% of 200 == 7% of 100 == 7Edit* as pointed out below, this one was incorrect.
14% of 200 == 28% of 100 == 28
You don’t have to stop at percentage either.
25 * 16 = 100 * 4
If you’re doing addition, you can add and subtract.
27 + 13 = 20 + 20
Most of the difficulty is in realizing that one number or the other can be brought up to a nice round number, making the equation simple to do in your head. And obviously, just getting to around number on one side doesn’t always make it easy on the other side.
I always loved screwing with math problems to make them easier, which is weird, because overall, I don’t really care for math.
I also do shit like borrowing a couple of numbers to make the equation easy and then pull them back out.
392 / 4 == (400 - 8) / 4 == (100-2) = 98
376 / 4 == (400-24)/4 =100-6=94
Of course it goes up a level when the remainder isn’t evenly divisible. But I still find it’s something I can handle in my head.
371 / 4 == (400-29)/4= 100-7¼ =100-7.25=92.75
14% of 200 == 28% of 100 == 28
You can also do 200% of 14, which I find more straightforward.
I would argue you’re still doing the other side just subliminally. But it is a fair point.
Why do you have to divide on both sides in your example with 14% of 200?
Oh shit, there I go getting along winded and get lost, yep, that should have been multiplied on the other side.
Are you just out here doing common core math on here like it’s just some smart trick to make math easier?! You dirty bastard, some conservative is going to see this and think it’s a good idea, then they’ll just innocently do it in front of their conservative friends and all hell will break loose. Homosexual fornication will suddenly run rampant through the group and those few that can resist the call of the devils numbers will have to cull the rest. You know… Actually… I am not completely against that now that I think about it…
Rofl, I pre-date common core. I’m not exactly sure to what extent they do all that stuff. I do know that they’ve got a fuck of a lot of numberlines, like so many number lines. Like they’re being paid by the number line.
Back in the 80s and 90s, the teachers would do regular scrolling down arithmetic, and they would mention borrowing numbers and shortcuts. And I took that shit seriously because I did not like sitting down and adding/multiplying numbers. I’d probably spend an extra 30 seconds of problem if I thought I could not have to sit down and write equations.
Babagedegaga. Ba.
23% of 53
53% of 23, next question
Pretty close to 1/4 of 52, so like 13-ish, but maybe closer to 12.
(13 + 0.25 - 0.53 - 0.53, really. If I had to, I might be able to keep that in my head.)
This is blowing my fucking mind like an artillery shell
It’s because percent just means ×0.01 and multiplication can be rearranged
Yeah, I personally find it a lot easier to compute 13% of 17, rather than 17% of 13.
Same with 375% of 20 rather than 20% of 375.
Damn, it still worked. Holy shit.
The few times I’ve seen you on Lemmy, it takes me a few seconds to process your username. Today, I had my favorite misreading yet: pronounced Ivana footerall
Thanks, now I can’t unsee that, fartographer
Are you a “silent fartographer”?
Seems pretty vocal to me.
I guess it’s easy to miss that m% just means ×m÷100
6% of 50 means 50 × 6 ÷ 100, and because multiplication and division have the same order of operations you can switch them around. so it is also equal to 6 × 50 ÷ 100, in which you can simplify 50 ÷ 100 into 1 ÷ 2, but you could always do that: 50 × 6 ÷ 100 = 1 × 6 ÷ 2.
this “shortcut” however is of extremely limited use. basically for taking a percentage of anything other than things that can very easily divide or multiply 100 like 50 in this example or maybe 10 or 500 it’s nearly useless.
Hence 90% of 6 is still hard.
Not really tho. If you know 9x6=54 then it’s pretty easy to get to 5.4 from there
8 and 8 fell on the floor, picked it up, it was 74.
Legitimately new knowledge for me that will literally make my work easier. Wish I could give you more than 100% of 1 upvote, OP!
1 of 100% upvote. Yeah, it checks out!
I wish someone told me this trick 30 years ago.
x/100 * y = x * 1/100 * y = x * y/100
I never would have thought of it myself and still feel like I should have thought of it myself.
So 37 % of 38 is equivalent to (37 * 38 ) / 100 ? Which I can almost do in my head.
37 * 4 is 148 I think, so 37 * 40 is 1480. Subtract 74 we have 1406. So we have 14.06?
You’re hired
For a while I’ve been meaning to memorize all the two digit squares but of course I then fail to practice them, so I’m not very far along. But that would help you with this too, not to mention you can start doing some square roots too.
For quick and dirty I’d probably just go with
37*38 = 40*40 -> 16%which is kinda close to 14% eh?Oh absolutely, depends on what you are measuring if that isn’t close enough
I’m gonna track down all my HS math teachers and punch each and every one of them in the mouth.
