What is 9/10 of 75?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 9/10 of 75? We'll show you a straightforward method to achieve that.

How to calculate 9/10 of 75?

  1. Multiply the whole number by the numerator of the fraction: 75 × 9 = 675
  2. Divide this result by denominator of the fraction: 675/10 = 67.5
  3. Simplify by dividing both the numerator and denominator by their GCD (5):
    • 675/5 = 135
    • 10/5 = 2
  4. Which gives: 135/2

Since 135/2 is an improper fraction, the result could also be expressed as a mixed number: 67 1/2

How does it work?

The principle behind finding a fraction of a number, such as 9/10 of 75, is rooted in the method of cross-multiplication.

Consider the following proportion: 9 10 = x 75 (where x represents 9/10 of 75)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 9 × 75 = 10 x
  2. Which gives: 675 = 10 x
  3. Divide both sides by 10 to isolate x: 675 10 = 10 x 10
  4. Which gives the result: 675 10 = x (or 135 2 = x )

Thus, 9/10 of 75 is equal to 135/2 (or 67.5 in its decimal form).