Question

How do you turn a percent into a decimal?

Answer 1

Divide by 100, so `40%=0.40`

Actually the word 'percent' means 'per 100' (maybe you recognize 'cent' as '100 in a dollar/euro/whatever').
So % is just short for "/100"

You might as well write `40%` as `40/100=0.40`

To turn a fraction into a percentage, you just do the reverse:

Multiply by 100, effectively doing `0.15=15/100=15%`

It's really that easy!