What is 4/1 of 81?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 4/1 of 81? We'll show you a straightforward method to achieve that.

How to calculate 4/1 of 81?

  1. Multiply the whole number by the numerator of the fraction: 81 × 4 = 324
  2. Divide this result by denominator of the fraction: 324/1 = 324

How does it work?

The principle behind finding a fraction of a number, such as 4/1 of 81, is rooted in the method of cross-multiplication.

Consider the following proportion: 4 1 = x 81 (where x represents 4/1 of 81)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 4 × 81 = 1 x
  2. Which gives: 324 = 1 x
  3. Divide both sides by 1 to isolate x: 324 1 = 1 x 1
  4. Which gives the result: 324 1 = x

Thus, 4/1 of 81 is equal to 324/1 (or 324 in its decimal form).