What is 8/10 of 39?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 8/10 of 39? We'll show you a straightforward method to achieve that.

How to calculate 8/10 of 39?

  1. Multiply the whole number by the numerator of the fraction: 39 × 8 = 312
  2. Divide this result by denominator of the fraction: 312/10 = 31.2
  3. Simplify by dividing both the numerator and denominator by their GCD (2):
    • 312/2 = 156
    • 10/2 = 5
  4. Which gives: 156/5

Since 156/5 is an improper fraction, the result could also be expressed as a mixed number: 31 1/5

How does it work?

The principle behind finding a fraction of a number, such as 8/10 of 39, is rooted in the method of cross-multiplication.

Consider the following proportion: 8 10 = x 39 (where x represents 8/10 of 39)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 8 × 39 = 10 x
  2. Which gives: 312 = 10 x
  3. Divide both sides by 10 to isolate x: 312 10 = 10 x 10
  4. Which gives the result: 312 10 = x (or 156 5 = x )

Thus, 8/10 of 39 is equal to 156/5 (or 31.2 in its decimal form).