What is 1/6 of 21?
Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 1/6 of 21? We'll show you a straightforward method to achieve that.
How to calculate 1/6 of 21?
- Multiply the whole number by the numerator of the fraction: 21 × 1 = 21
- Divide this result by denominator of the fraction: 21/6 = 3.5
- Simplify by dividing both the numerator and denominator by their GCD (3):
- 21/3 = 7
- 6/3 = 2
- Which gives: 7/2
Since 7/2 is an improper fraction, the result could also be expressed as a mixed number: 3 1/2
How does it work?
The principle behind finding a fraction of a number, such as 1/6 of 21, is rooted in the method of cross-multiplication.
Consider the following proportion: (where x represents 1/6 of 21)
- Using the cross-multiplication method, multiply both numerators by their opposite denominators:
- Which gives:
- Divide both sides by 6 to isolate x:
- Which gives the result: (or )
Thus, 1/6 of 21 is equal to 7/2 (or 3.5 in its decimal form).