What is 1/6 of 21?

How to calculate 1/6 of 21?

1. Multiply the whole number by the numerator of the fraction: 21 × 1 = 21
2. Divide this result by denominator of the fraction: 21/6 = 3.5
3. Simplify by dividing both the numerator and denominator by their GCD (3):
   • 21/3 = 7
   • 6/3 = 2
4. 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: $\frac{1}{6}=\frac{x}{21}$ (where x represents 1/6 of 21)

1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: $1\times 21=6x$
2. Which gives: $21=6x$
3. Divide both sides by 6 to isolate x: $\frac{21}{6}=\frac{6x}{6}$
4. Which gives the result: $\frac{21}{6}=x$ (or $\frac{7}{2}=x$)

Thus, 1/6 of 21 is equal to 7/2 (or 3.5 in its decimal form).