What is 9/10 of 99?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 9/10 of 99? We'll show you a straightforward method to achieve that.

How to calculate 9/10 of 99?

  1. Multiply the whole number by the numerator of the fraction: 99 × 9 = 891
  2. Divide this result by denominator of the fraction: 891/10 = 89.1

Since 891/10 is an improper fraction, the result could also be expressed as a mixed number: 89 1/10

How does it work?

The principle behind finding a fraction of a number, such as 9/10 of 99, is rooted in the method of cross-multiplication.

Consider the following proportion: 9 10 = x 99 (where x represents 9/10 of 99)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 9 × 99 = 10 x
  2. Which gives: 891 = 10 x
  3. Divide both sides by 10 to isolate x: 891 10 = 10 x 10
  4. Which gives the result: 891 10 = x

Thus, 9/10 of 99 is equal to 891/10 (or 89.1 in its decimal form).