What is 15 out of 20 as a percentage?

Well 20 goes into 100, 5 times.... so if you multiply the number out of 20(in this case, 15) by 5 you get you percentage.

Or you could just multiply 15/20(fraction) by 5.

15/20x5= 75% 20x5=100... so 15x5= 75% :)

its really simple.

Alternatively just do 15/20 and times by 100. Essentially that is what has happened above but that method is unnecessarily complicated for larger numbers if you don't know their factors/multiples.