What is 1/2 of 40?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 1/2 of 40? We'll show you a straightforward method to achieve that.

How to calculate 1/2 of 40?

  1. Multiply the whole number by the numerator of the fraction: 40 × 1 = 40
  2. Divide this result by denominator of the fraction: 40/2 = 20
  3. Simplify by dividing both the numerator and denominator by their GCD (2):
    • 40/2 = 20
    • 2/2 = 1
  4. Which gives: 20/1

How does it work?

The principle behind finding a fraction of a number, such as 1/2 of 40, is rooted in the method of cross-multiplication.

Consider the following proportion: 1 2 = x 40 (where x represents 1/2 of 40)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 1 × 40 = 2 x
  2. Which gives: 40 = 2 x
  3. Divide both sides by 2 to isolate x: 40 2 = 2 x 2
  4. Which gives the result: 40 2 = x (or 20 1 = x )

Thus, 1/2 of 40 is equal to 20/1 (or 20 in its decimal form).