What is 8/7 of 81?

How to calculate 8/7 of 81?

1. Multiply the whole number by the numerator of the fraction: 81 × 8 = 648
2. Divide this result by denominator of the fraction: 648/7 = 92.571428571429

Since 648/7 is an improper fraction, the result could also be expressed as a mixed number: 92 4/7

How does it work?

The principle behind finding a fraction of a number, such as 8/7 of 81, is rooted in the method of cross-multiplication.

Consider the following proportion: $\frac{8}{7}=\frac{x}{81}$ (where x represents 8/7 of 81)

1. Using the cross-multiplication method, multiply both numerators by their opposite denominators: $8\times 81=7x$
2. Which gives: $648=7x$
3. Divide both sides by 7 to isolate x: $\frac{648}{7}=\frac{7x}{7}$
4. Which gives the result: $\frac{648}{7}=x$

Thus, 8/7 of 81 is equal to 648/7 (or 92.571428571429 in its decimal form).