What is 7/10 of 45?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 7/10 of 45? We'll show you a straightforward method to achieve that.

How to calculate 7/10 of 45?

  1. Multiply the whole number by the numerator of the fraction: 45 × 7 = 315
  2. Divide this result by denominator of the fraction: 315/10 = 31.5
  3. Simplify by dividing both the numerator and denominator by their GCD (5):
    • 315/5 = 63
    • 10/5 = 2
  4. Which gives: 63/2

Since 63/2 is an improper fraction, the result could also be expressed as a mixed number: 31 1/2

How does it work?

The principle behind finding a fraction of a number, such as 7/10 of 45, is rooted in the method of cross-multiplication.

Consider the following proportion: 7 10 = x 45 (where x represents 7/10 of 45)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 7 × 45 = 10 x
  2. Which gives: 315 = 10 x
  3. Divide both sides by 10 to isolate x: 315 10 = 10 x 10
  4. Which gives the result: 315 10 = x (or 63 2 = x )

Thus, 7/10 of 45 is equal to 63/2 (or 31.5 in its decimal form).