scored / total x 100
e.g. if you score 18 out of 20 for a test, then its:
18 / 20 * 100 = 90%
if you have the percentage then its:
% / 100 x number =
e.g. 90% of 20 is:
90 / 100 * 20 = 18
and by the way to the other answer: Percentage is a english word, it is in the dictionary, and is defined as: noun "part of total divided by 100. maths an amount or rate that is equal to a particular part of a total that you have divided by 100" - encarta: english (U.K) provided by microsoft word