The "life-changing" math hack for percentages they probably didn’t teach you in school

When you’re learning how to add and subtract at 7 years, followed shortly by your times tables in Grades 2 and 3, mathematical concepts in primary school can seem somewhat easy. You’re using an abacus and cracking jokes about why 6 is afraid of 7 – because 7, 8 (ate), 9 – gets me every time!

But oftentimes maths becomes our least favourite subject, what with us having to trade our abacuses for calculators and our 7s, 8s and 9s for bigger, badder numbers. Throw percentages in the mix, and suddenly, we forget everything we were taught.

Twitter user Ben Stephens recently “[set] the internet on fire” though after tweeting one “fascinating little life hack” for percentages that the internet has sinced deemed "life-changing"

“x% of y = y% of x 

Ben explained that if kids are struggling to work out a percentage of a number, they can swap the two numbers around to make things easier because the answer will still be the same. 

“For example, if you needed to work out 4% of 75 in your head,” he says, “Just flip it and do 75% of 4, which is easier.” 

And it’s true – the answer is 3 both ways. 

We worked out a few more to really test his maths hack: 

24% of 50 = 50% of 24 = 12 
20% of 75 = 75% of 20 = 15 
15% of 20 = 20% of 15 = 3  


So how old were you when you discovered this math hack? Because I was today years old. 

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Do you have any other cool maths hacks? Tell us and we may share them with our readers.

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