What is 5/10 of 85?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 5/10 of 85? We'll show you a straightforward method to achieve that.

How to calculate 5/10 of 85?

  1. Multiply the whole number by the numerator of the fraction: 85 × 5 = 425
  2. Divide this result by denominator of the fraction: 425/10 = 42.5
  3. Simplify by dividing both the numerator and denominator by their GCD (5):
    • 425/5 = 85
    • 10/5 = 2
  4. Which gives: 85/2

Since 85/2 is an improper fraction, the result could also be expressed as a mixed number: 42 1/2

How does it work?

The principle behind finding a fraction of a number, such as 5/10 of 85, is rooted in the method of cross-multiplication.

Consider the following proportion: 5 10 = x 85 (where x represents 5/10 of 85)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 5 × 85 = 10 x
  2. Which gives: 425 = 10 x
  3. Divide both sides by 10 to isolate x: 425 10 = 10 x 10
  4. Which gives the result: 425 10 = x (or 85 2 = x )

Thus, 5/10 of 85 is equal to 85/2 (or 42.5 in its decimal form).