What is 1/7 of 80?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 1/7 of 80? We'll show you a straightforward method to achieve that.

How to calculate 1/7 of 80?

  1. Multiply the whole number by the numerator of the fraction: 80 × 1 = 80
  2. Divide this result by denominator of the fraction: 80/7 = 11.428571428571

Since 80/7 is an improper fraction, the result could also be expressed as a mixed number: 11 3/7

How does it work?

The principle behind finding a fraction of a number, such as 1/7 of 80, is rooted in the method of cross-multiplication.

Consider the following proportion: 1 7 = x 80 (where x represents 1/7 of 80)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 1 × 80 = 7 x
  2. Which gives: 80 = 7 x
  3. Divide both sides by 7 to isolate x: 80 7 = 7 x 7
  4. Which gives the result: 80 7 = x

Thus, 1/7 of 80 is equal to 80/7 (or 11.428571428571 in its decimal form).