Calculating percentage from a decimal or a fraction requires multiplying by 100. For a decimal, this means moving the decimal point two places to the right; for example, .28 equals 28 percent. To convert fractions, the numerator is divided by the denominator and the quotient is multiplied by 100.
Dividing the numerator of a fraction by the denominator rewrites the fraction as a decimal. For example, the fraction 3/4 is another way of saying 3 divided by 4, which yields a quotient of .75. Since .75 x 100 = 75, 3/4 = 75 percent. This same answer can also be found by multiplying the fraction by 100 and reducing, since 3/4 x 100 = 300/4, and 300/4 reduces to 75.