What is 5/7 of 77?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 5/7 of 77? We'll show you a straightforward method to achieve that.

How to calculate 5/7 of 77?

  1. Multiply the whole number by the numerator of the fraction: 77 × 5 = 385
  2. Divide this result by denominator of the fraction: 385/7 = 55
  3. Simplify by dividing both the numerator and denominator by their GCD (7):
    • 385/7 = 55
    • 7/7 = 1
  4. Which gives: 55/1

How does it work?

The principle behind finding a fraction of a number, such as 5/7 of 77, is rooted in the method of cross-multiplication.

Consider the following proportion: 5 7 = x 77 (where x represents 5/7 of 77)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 5 × 77 = 7 x
  2. Which gives: 385 = 7 x
  3. Divide both sides by 7 to isolate x: 385 7 = 7 x 7
  4. Which gives the result: 385 7 = x (or 55 1 = x )

Thus, 5/7 of 77 is equal to 55/1 (or 55 in its decimal form).