What is 9/1 of 21?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 9/1 of 21? We'll show you a straightforward method to achieve that.

How to calculate 9/1 of 21?

  1. Multiply the whole number by the numerator of the fraction: 21 × 9 = 189
  2. Divide this result by denominator of the fraction: 189/1 = 189

How does it work?

The principle behind finding a fraction of a number, such as 9/1 of 21, is rooted in the method of cross-multiplication.

Consider the following proportion: 9 1 = x 21 (where x represents 9/1 of 21)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 9 × 21 = 1 x
  2. Which gives: 189 = 1 x
  3. Divide both sides by 1 to isolate x: 189 1 = 1 x 1
  4. Which gives the result: 189 1 = x

Thus, 9/1 of 21 is equal to 189/1 (or 189 in its decimal form).