What is 1/9 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 1/9 of 80? We'll show you a straightforward method to achieve that.

How to calculate 1/9 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: 80/9 = 8.8888888888889

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

How does it work?

The principle behind finding a fraction of a number, such as 1/9 of 80, is rooted in the method of cross-multiplication.

Consider the following proportion: 1 9 = x 80 (where x represents 1/9 of 80)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 1 × 80 = 9 x
  2. Which gives: 80 = 9 x
  3. Divide both sides by 9 to isolate x: 80 9 = 9 x 9
  4. Which gives the result: 80 9 = x

Thus, 1/9 of 80 is equal to 80/9 (or 8.8888888888889 in its decimal form).