What is 9/5 of 42?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 9/5 of 42? We'll show you a straightforward method to achieve that.

How to calculate 9/5 of 42?

  1. Multiply the whole number by the numerator of the fraction: 42 × 9 = 378
  2. Divide this result by denominator of the fraction: 378/5 = 75.6

Since 378/5 is an improper fraction, the result could also be expressed as a mixed number: 75 3/5

How does it work?

The principle behind finding a fraction of a number, such as 9/5 of 42, is rooted in the method of cross-multiplication.

Consider the following proportion: 9 5 = x 42 (where x represents 9/5 of 42)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 9 × 42 = 5 x
  2. Which gives: 378 = 5 x
  3. Divide both sides by 5 to isolate x: 378 5 = 5 x 5
  4. Which gives the result: 378 5 = x

Thus, 9/5 of 42 is equal to 378/5 (or 75.6 in its decimal form).