We all sometimes struggle calculating simple percentages in our head, whether it is to find how much we could save on a discounted sale or in calculating simple percentage returns on any investment we are likely to make. Nevertheless, this trick from a self-confessed “maths wizard” Ben Stephens, might make it easier than we think.
Stephens recently tweeted a mind-blowing math trick on how to calculate percentages in your head. His surprisingly simple solution has now gone viral and left a lot of people wondering why it wasn’t taught at school.
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.
So what’s the key formula? It’s simple: x% of y = y% of x. Stephens explains, So, as an example, if you are required to figure out 4% of 75 in your head, simply flip it and do 75% of 4, which is less complicated. If you haven’t already worked it out, the solution is 3, and therefore this straightforward trick can be applied to any set of numbers. 18% of 50 feels onerous to calculate. Nonetheless, 50% of 18 is easier, right? you got it, it is 9 indeed.
Like multiplication, percentages conform to the commutative principle, which says the order of the terms does not matter. (Just as
, it is also true that 40% of 5 = 5% of 40).
So the secret here is flipping the numbers around :). So try it out for yourself and share it with others!!