If you’re on social media lately, you might have seen this twitter post that has gone viral.
This is indeed a percentage conversion identity that can be especially handy when you have to do mental calculations involving percentages.
x% of y = y% of x
This comes from the fact that percentage is nothing but a fraction of 100, i.e. x% = x/100. Hence,
(x/100) × y = (x × y)/100 = (y × x)/100 = (y/100) × x
This mental math trick is especially useful if both numbers are less than 100, e.g.
4% of 75 = 75% of 4.
Isn’t it great? Thanks to Ben for sharing!