What is 8/9 of 91?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 8/9 of 91? We'll show you a straightforward method to achieve that.

How to calculate 8/9 of 91?

  1. Multiply the whole number by the numerator of the fraction: 91 × 8 = 728
  2. Divide this result by denominator of the fraction: 728/9 = 80.888888888889

Since 728/9 is an improper fraction, the result could also be expressed as a mixed number: 80 8/9

How does it work?

The principle behind finding a fraction of a number, such as 8/9 of 91, is rooted in the method of cross-multiplication.

Consider the following proportion: 8 9 = x 91 (where x represents 8/9 of 91)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 8 × 91 = 9 x
  2. Which gives: 728 = 9 x
  3. Divide both sides by 9 to isolate x: 728 9 = 9 x 9
  4. Which gives the result: 728 9 = x

Thus, 8/9 of 91 is equal to 728/9 (or 80.888888888889 in its decimal form).