What is 9/8 of 15?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 9/8 of 15? We'll show you a straightforward method to achieve that.

How to calculate 9/8 of 15?

  1. Multiply the whole number by the numerator of the fraction: 15 × 9 = 135
  2. Divide this result by denominator of the fraction: 135/8 = 16.875

Since 135/8 is an improper fraction, the result could also be expressed as a mixed number: 16 7/8

How does it work?

The principle behind finding a fraction of a number, such as 9/8 of 15, is rooted in the method of cross-multiplication.

Consider the following proportion: 9 8 = x 15 (where x represents 9/8 of 15)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 9 × 15 = 8 x
  2. Which gives: 135 = 8 x
  3. Divide both sides by 8 to isolate x: 135 8 = 8 x 8
  4. Which gives the result: 135 8 = x

Thus, 9/8 of 15 is equal to 135/8 (or 16.875 in its decimal form).