What is 2/8 of 81?

How to calculate 2/8 of 81?

1. Multiply the whole number by the numerator of the fraction: 81 × 2 = 162
2. Divide this result by denominator of the fraction: 162/8 = 20.25
3. Simplify by dividing both the numerator and denominator by their GCD (2):
   • 162/2 = 81
   • 8/2 = 4
4. Which gives: 81/4

Since 81/4 is an improper fraction, the result could also be expressed as a mixed number: 20 1/4

How does it work?

The principle behind finding a fraction of a number, such as 2/8 of 81, is rooted in the method of cross-multiplication.

Consider the following proportion: $\frac{2}{8}=\frac{x}{81}$ (where x represents 2/8 of 81)

1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: $2\times 81=8x$
2. Which gives: $162=8x$
3. Divide both sides by 8 to isolate x: $\frac{162}{8}=\frac{8x}{8}$
4. Which gives the result: $\frac{162}{8}=x$ (or $\frac{81}{4}=x$)

Thus, 2/8 of 81 is equal to 81/4 (or 20.25 in its decimal form).