What is 5/9 of 31?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 5/9 of 31? We'll show you a straightforward method to achieve that.

How to calculate 5/9 of 31?

  1. Multiply the whole number by the numerator of the fraction: 31 × 5 = 155
  2. Divide this result by denominator of the fraction: 155/9 = 17.222222222222

Since 155/9 is an improper fraction, the result could also be expressed as a mixed number: 17 2/9

How does it work?

The principle behind finding a fraction of a number, such as 5/9 of 31, is rooted in the method of cross-multiplication.

Consider the following proportion: 5 9 = x 31 (where x represents 5/9 of 31)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 5 × 31 = 9 x
  2. Which gives: 155 = 9 x
  3. Divide both sides by 9 to isolate x: 155 9 = 9 x 9
  4. Which gives the result: 155 9 = x

Thus, 5/9 of 31 is equal to 155/9 (or 17.222222222222 in its decimal form).