What is 8/9 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 8/9 of 45? We'll show you a straightforward method to achieve that.

How to calculate 8/9 of 45?

  1. Multiply the whole number by the numerator of the fraction: 45 × 8 = 360
  2. Divide this result by denominator of the fraction: 360/9 = 40
  3. Simplify by dividing both the numerator and denominator by their GCD (9):
    • 360/9 = 40
    • 9/9 = 1
  4. Which gives: 40/1

How does it work?

The principle behind finding a fraction of a number, such as 8/9 of 45, is rooted in the method of cross-multiplication.

Consider the following proportion: 8 9 = x 45 (where x represents 8/9 of 45)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 8 × 45 = 9 x
  2. Which gives: 360 = 9 x
  3. Divide both sides by 9 to isolate x: 360 9 = 9 x 9
  4. Which gives the result: 360 9 = x (or 40 1 = x )

Thus, 8/9 of 45 is equal to 40/1 (or 40 in its decimal form).