What is 1/4 of 85?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 1/4 of 85? We'll show you a straightforward method to achieve that.

How to calculate 1/4 of 85?

  1. Multiply the whole number by the numerator of the fraction: 85 × 1 = 85
  2. Divide this result by denominator of the fraction: 85/4 = 21.25

Since 85/4 is an improper fraction, the result could also be expressed as a mixed number: 21 1/4

How does it work?

The principle behind finding a fraction of a number, such as 1/4 of 85, is rooted in the method of cross-multiplication.

Consider the following proportion: 1 4 = x 85 (where x represents 1/4 of 85)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 1 × 85 = 4 x
  2. Which gives: 85 = 4 x
  3. Divide both sides by 4 to isolate x: 85 4 = 4 x 4
  4. Which gives the result: 85 4 = x

Thus, 1/4 of 85 is equal to 85/4 (or 21.25 in its decimal form).