What is 9/4 of 57?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 9/4 of 57? We'll show you a straightforward method to achieve that.

How to calculate 9/4 of 57?

  1. Multiply the whole number by the numerator of the fraction: 57 × 9 = 513
  2. Divide this result by denominator of the fraction: 513/4 = 128.25

Since 513/4 is an improper fraction, the result could also be expressed as a mixed number: 128 1/4

How does it work?

The principle behind finding a fraction of a number, such as 9/4 of 57, is rooted in the method of cross-multiplication.

Consider the following proportion: 9 4 = x 57 (where x represents 9/4 of 57)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 9 × 57 = 4 x
  2. Which gives: 513 = 4 x
  3. Divide both sides by 4 to isolate x: 513 4 = 4 x 4
  4. Which gives the result: 513 4 = x

Thus, 9/4 of 57 is equal to 513/4 (or 128.25 in its decimal form).