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transitive and commutative
In either case I would multiply 5 by 6 and move the decimal. Interesting though.
6 of 50 is 300. % just means 1/100. That’s also a good way to think of it.
Let’s try this on a sale item. Hmm, let’s see, the sign says 25% off $6.99. So that’s the same as, let’s say, 7% off $25. Oh, yeah, that is much easier. /s
Wait…
So 25% off $100… is 100% off $25! TrollfaceI mean if you remove the word off it works. 25% off $100 is $25 100% of 25 is 25 it’s still reversible you just let the word off confuse you
You could also make sure to carry “off” to both sides when you swap:
off of $100 is 100% of $25 off
Another counter-intuitive percentage fact: A 10 percent discount and a 10 percent fee can be calculated in either order but they don’t cancel out.
Example, 90% of (110% of 10) = 110% of (90% of 10). But neither of those is evaluates to 10. They evaluate to 9.9.
For any percentage X, and and base value C, (100 - X)% x ((100 + X)% x C) = (100 + X)% x ((100 - X)% x C) = (100 - (X^2/100))% x C
This one irks me to no end.
Everyone’s talking about this math. I’m wondering about the panzer.
They said the water could reach up to 50% of its 1.7 meter height before causing problems, panzer tried calculating 1.7% of 50 meters from head, this is the result.
Strange Panzers lying in ponds distributing shells is no basis for a system of government…
Surely you don’t think supreme executive power derives from a mandate from the masses?
I thought we were an autonomous collective
As opposed to what, a farcical aquatic ceremony?
That was unexpected.
And now for something completely different
No one expects the python imposition!
This is far too useful to be a shitpost.
it’s very often not useful. Like, what’s 6% of 80? See. Still hard.
Also, with the 6% of 50 example it’s easy without using this trick.
What’s 6% of 100? 6, right? So cut 100 in half to get to 50, and cut the 6 in half to get the 3. Cut the 50 in half again and cut the 3 in half again, and you’ll also know that 6% of 25 is 1.5.
Which also lets you know that 6% of 75 is 4.5. the 3 from the 50, plus the 1.5 from the 25. or just know to split the difference between the 3 at 50 and the 6 at 100.
A lot of math is just tricks for a thinking process.
Good luck explaining your supreme methodology to anyone that isn’t a geek.
It’s stupid simple… If you know 6% of one hundred is 6, then you should know 6% of 50 is 3. You just cut each number in half.
I know right. I even open the calculator app to verify before committing to memory this nugget.
Barely, only if you choose round and small numbers. 67% of 347 or 347% of 67 which one is easier?
347 is pretty damn close to 350.
350% of 67 =3.5 x 67 ~ 180+21+33=234
Within 1% is pretty good!
SPEAK ENGLISH! Jeez
I was waiting in a car in front of a math tutoring building and was doing the math problems advertised on their window (as one does, of course) and the 7% of 250 is indeed probably easiest as 250% of 7, aka 2.5x7, which is 17.5.
I did it a few other ways, though. 7% of 1000 is 70, then divide by 4 for 17.5. Well, more like, divide by 2 for 35 and again for 17.5, but yeah… mental math is fun.
👆 This guy… fucks?
Calcufucks?
6% of 50
6/100 * 50/1
(6 * 50) / (100 * 1)
(50 * 6) / (100 * 1)
50/100 * 6/1
50% of 6
Works for multiplying any fraction, not just percents.
2/3 of 5 is the same as 5/3 of 2.
2/5 of 7/8 is the same as 7/5 of 2/8.
How is 17% of 83.27 easier then 83.27% of 17?
Oddly, yes.
Percentages also add together in partials. As in 10%+5%+2% = 17%
So, you start with the 10% by moving the decimal over 83.27 becomes 8.327
Then add half of that (5%) to its self and get 12.49 (rounded)
Then take the 10% number and move the decimal over once more (1%) for 0.833 and double it (from 1% to 2%) and get 1.666 and add that to your running total to get your answer of 14.16 (rounding)
And when I calculator check this I got 14.1559.
Yo what
So 50% of 50 is the same as 50% of 50. Both equal 5
Both equal 5
More like 5 of these
5 sweet dreams, got it
Who am I to disagree
And the other half is 0! 5 0
0! is 0.
Edit. I remembered wrong. Keeping it like this as it is funnier that way.
factorials are mostly encountered in combinatorics, which is problems like, how many ways are there to put 3 objects of different colors in a row? well, the first can be any of the 3, the second can be either of the other 2, and the last is whichever 1 is left, so 3×2×1=3!=6
so how many ways are there to put 0 objects in a row? well there’s 1, it’s this one:
that’s why 0!=1
Wow, that was a really great explanation! Thanks! I could have needed this twenty years ago and maybe we wouldn’t have had this interaction.
Man math is hard
I love this so much
00 is 1.
Depends on context.
Dammit, you’re right!
Caught me by complete surprise too, when I first learned it. It’s undefined in most areas of math, I think, but in some it’s just following the convention, it seems:
- 42 = 16,
- 41 = 4,
- n0 = 1,
- 0 x 0 = 0
real
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Multiplication is commutative.
50% of 6 == 50/100 x 6 == (50 x 6)/100 == 50 x 6/100 == 6% of 50.
True
taking x% is just multiplying by x/100, and multiplication is commutative. x% of y is just y×x×1/100, which is the same as x×y×1/100
you can also ignore the % and divide by 100 at the end. for example, what’s 5% of 5? that might take a minute to work out. what’s 25/100? you instantly know it’s 1/4
Percentages can be expressed as multiplication and multiplication is commutative (the order doesn’t matter).
Great for calculating tips!
Let’s see: the bill was $138.72, so I just need 138.72% of 20. And we can subtract 100% and just add the 20 back at the end, then convert the percentage to a decimal so (.3872 * 20) + 20 = 7.744 + 20 or $27.74.
Easy!
I prefer taking 10% and doubling it for a 20% tip.
Take the total, moved the decimal one digit to the left, double it and round to the nearest dollar. I round up at the beginning and end as well which is either close enough or a dollar high if the change is small enough.
$138.72 > 139 > 13.9 > 27.8 > $28
Close enough!
I either do this, or mentally divide by 5 (how many 5s make this number?), only caring about the closest whole number - I prefer to tip in whole dollar amounts to make the math easy.
Eg. $39.53 is about $40, 40 is 8 fives, so tip $8
If the service wasn’t great I round down instead of up.
I multiply the tip by 5 to double check my math which is how I know it comes out as a dolllar higher sometimes.
28x5=140
I always just do 10% (easy because you move the decimal one place) and then either double that or add half of it to itself for a 15-20% tip.
For sure. Reversing the percentages here makes this far more difficult. I just felt we needed to shittify this post a little.
i just do 0. I feel like giving 20% more than agreed upon as default is crazy. I can not imagine employers giving 20% more wages just because i was doing my job? Why should i burn money?
I tip because I’ve been reliant on tips before, and I know that expecting someone who is working for tips to single-handedly solve tipping culture is unreasonable. I don’t believe in solutions that punish the poorest person in the equation, especially for a luxury like dining out.
You can already eat at places that pay a real wage to servers if you don’t want to tip.
I hate math so much.
Thank you for thisThis is probably only useful when you’re finding percentages of 50 or 100.
No way! 68% of 120 is 120% of 68, so drop the 100% now i just need to figure out 20% of 68 or do i need 68% of 20 which is really just 6 tens plus 8% so divide 20 by 10, then times 6 which is 12, now we need 8% of 20 which is just 20% of 8 or whichdies
Panzer: Going tip to tip changes meaning the larger one of the participates is.
