This maths hack taking the pain out of percentages is blowing people’s minds
Sometimes, just sometimes, Twitter is there for the good things in life. This is one of those times.
Fascinating little life hack, for doing percentages:
x% of y = y% of x
So, for example, if you needed to work out 4% of 75 in your head, just flip it and and do 75% of 4, which is easier.
— Ben Stephens (@stephens_ben) March 3, 2019
We keep doing sums to make sure it’s right. Very simple sums, mind. And it appears to be true.
umm so is the answer 3? The suspense is killing me.
— london (@Shehzaadi_kris) March 3, 2019
It is!
18% of 50 feels hard to calculate.
But 50% of 18 is a doddle, right?— Ben Stephens (@stephens_ben) March 3, 2019
And it’s not only our mind that was blown.
As someone who Quite Likes Maths I cannot believe I hadn’t realised this until the age of 47. https://t.co/4MFf8DuB6s
— Rhodri Marsden ⏏️ (@rhodri) March 6, 2019
This is the day Twitter changed my life.
I earn a living as a scientist, juggling numbers every day, and I have never realised this:
X percent of Y is equal to Y percent of X
7% of 50 = 50% of 7 = 3.5
Not sure whether I should be happy or embarrassed… Maybe both. https://t.co/0rpVaJgPUh
— Antoine van Oijen 🔬🧫🧬 (@van__Oijen) March 5, 2019
How did I not know this? 😃 https://t.co/Cf3O8D5H9R
— Hasu⚡️🤖 (@hasufl) March 5, 2019
God. Damn. https://t.co/JW0mTvhMDF
— Anne Hilborn (@AnneWHilborn) March 5, 2019
More maths sorcery! @SLSingh https://t.co/csU7BbK9PA
— Prof Alice Roberts (@theAliceRoberts) March 5, 2019
And in case you’re one of those people that would like to see the proof, here you go.
Basic arithmetic isn't a "life hack", but OK. Here's a proof. Just rearrange multiplication.
x% of y = (0.01 * x) * y = x * (0.01 * y) = y% of x
The proof reveals another move: if x% of y is hard and y% of x is hard, try multiplying x*y and dividing by 100. E.g., 12% of 12. https://t.co/92uO899DxS
— Jeremy Kun ([email protected]) (@jeremyjkun) March 5, 2019
We’re going to level with you here, that just confused us further.
Yes, it's fascinating that it's fascinating. If you say x * y = y * x, it's obvious. Even x/100 * y = y/100 * x seems unremarkable. But we don't think of the % operator as a form of multiplication, so the commutativity comes as a surprise. https://t.co/raSMaVblBq
— Brian Hayes (@bit_player) March 3, 2019
So did that …
