What is 3/7 of 45?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 3/7 of 45? We'll show you a straightforward method to achieve that.

How to calculate 3/7 of 45?

  1. Multiply the whole number by the numerator of the fraction: 45 × 3 = 135
  2. Divide this result by denominator of the fraction: 135/7 = 19.285714285714

Since 135/7 is an improper fraction, the result could also be expressed as a mixed number: 19 2/7

How does it work?

The principle behind finding a fraction of a number, such as 3/7 of 45, is rooted in the method of cross-multiplication.

Consider the following proportion: 3 7 = x 45 (where x represents 3/7 of 45)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 3 × 45 = 7 x
  2. Which gives: 135 = 7 x
  3. Divide both sides by 7 to isolate x: 135 7 = 7 x 7
  4. Which gives the result: 135 7 = x

Thus, 3/7 of 45 is equal to 135/7 (or 19.285714285714 in its decimal form).