What is 1/5 of 20?
Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 1/5 of 20? We'll show you a straightforward method to achieve that.
How to calculate 1/5 of 20?
- Multiply the whole number by the numerator of the fraction: 20 × 1 = 20
- Divide this result by denominator of the fraction: 20/5 = 4
- Simplify by dividing both the numerator and denominator by their GCD (5):
- 20/5 = 4
- 5/5 = 1
- Which gives: 4/1
How does it work?
The principle behind finding a fraction of a number, such as 1/5 of 20, is rooted in the method of cross-multiplication.
Consider the following proportion: (where x represents 1/5 of 20)
- Using the cross-multiplication method, multiply both numerators by their opposite denominators:
- Which gives:
- Divide both sides by 5 to isolate x:
- Which gives the result: (or )
Thus, 1/5 of 20 is equal to 4/1 (or 4 in its decimal form).