What is 3/10 of 70?

Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 3/10 of 70? We'll show you a straightforward method to achieve that.

How to calculate 3/10 of 70?

  1. Multiply the whole number by the numerator of the fraction: 70 × 3 = 210
  2. Divide this result by denominator of the fraction: 210/10 = 21
  3. Simplify by dividing both the numerator and denominator by their GCD (10):
    • 210/10 = 21
    • 10/10 = 1
  4. Which gives: 21/1

How does it work?

The principle behind finding a fraction of a number, such as 3/10 of 70, is rooted in the method of cross-multiplication.

Consider the following proportion: 3 10 = x 70 (where x represents 3/10 of 70)

  1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: 3 × 70 = 10 x
  2. Which gives: 210 = 10 x
  3. Divide both sides by 10 to isolate x: 210 10 = 10 x 10
  4. Which gives the result: 210 10 = x (or 21 1 = x )

Thus, 3/10 of 70 is equal to 21/1 (or 21 in its decimal form).