What is 1/4 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 1/4 of 80? We'll show you a straightforward method to achieve that.

How to calculate 1/4 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: 80/4 = 20
  3. Simplify by dividing both the numerator and denominator by their GCD (4):
    • 80/4 = 20
    • 4/4 = 1
  4. Which gives: 20/1

How does it work?

The principle behind finding a fraction of a number, such as 1/4 of 80, is rooted in the method of cross-multiplication.

Consider the following proportion: 1 4 = x 80 (where x represents 1/4 of 80)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 1 × 80 = 4 x
  2. Which gives: 80 = 4 x
  3. Divide both sides by 4 to isolate x: 80 4 = 4 x 4
  4. Which gives the result: 80 4 = x (or 20 1 = x )

Thus, 1/4 of 80 is equal to 20/1 (or 20 in its decimal form).