What is 8/9 of 78?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 8/9 of 78? We'll show you a straightforward method to achieve that.

How to calculate 8/9 of 78?

  1. Multiply the whole number by the numerator of the fraction: 78 × 8 = 624
  2. Divide this result by denominator of the fraction: 624/9 = 69.333333333333
  3. Simplify by dividing both the numerator and denominator by their GCD (3):
    • 624/3 = 208
    • 9/3 = 3
  4. Which gives: 208/3

Since 208/3 is an improper fraction, the result could also be expressed as a mixed number: 69 1/3

How does it work?

The principle behind finding a fraction of a number, such as 8/9 of 78, is rooted in the method of cross-multiplication.

Consider the following proportion: 8 9 = x 78 (where x represents 8/9 of 78)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 8 × 78 = 9 x
  2. Which gives: 624 = 9 x
  3. Divide both sides by 9 to isolate x: 624 9 = 9 x 9
  4. Which gives the result: 624 9 = x (or 208 3 = x )

Thus, 8/9 of 78 is equal to 208/3 (or 69.333333333333 in its decimal form).