What is 9/2 of 87?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 9/2 of 87? We'll show you a straightforward method to achieve that.

How to calculate 9/2 of 87?

  1. Multiply the whole number by the numerator of the fraction: 87 × 9 = 783
  2. Divide this result by denominator of the fraction: 783/2 = 391.5

Since 783/2 is an improper fraction, the result could also be expressed as a mixed number: 391 1/2

How does it work?

The principle behind finding a fraction of a number, such as 9/2 of 87, is rooted in the method of cross-multiplication.

Consider the following proportion: 9 2 = x 87 (where x represents 9/2 of 87)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 9 × 87 = 2 x
  2. Which gives: 783 = 2 x
  3. Divide both sides by 2 to isolate x: 783 2 = 2 x 2
  4. Which gives the result: 783 2 = x

Thus, 9/2 of 87 is equal to 783/2 (or 391.5 in its decimal form).