What is 5/7 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 5/7 of 15? We'll show you a straightforward method to achieve that.

How to calculate 5/7 of 15?

  1. Multiply the whole number by the numerator of the fraction: 15 × 5 = 75
  2. Divide this result by denominator of the fraction: 75/7 = 10.714285714286

Since 75/7 is an improper fraction, the result could also be expressed as a mixed number: 10 5/7

How does it work?

The principle behind finding a fraction of a number, such as 5/7 of 15, is rooted in the method of cross-multiplication.

Consider the following proportion: 5 7 = x 15 (where x represents 5/7 of 15)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 5 × 15 = 7 x
  2. Which gives: 75 = 7 x
  3. Divide both sides by 7 to isolate x: 75 7 = 7 x 7
  4. Which gives the result: 75 7 = x

Thus, 5/7 of 15 is equal to 75/7 (or 10.714285714286 in its decimal form).