What is 1/8 of 81?
Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 1/8 of 81? We'll show you a straightforward method to achieve that.
How to calculate 1/8 of 81?
- Multiply the whole number by the numerator of the fraction: 81 × 1 = 81
- Divide this result by denominator of the fraction: 81/8 = 10.125
Since 81/8 is an improper fraction, the result could also be expressed as a mixed number: 10 1/8
How does it work?
The principle behind finding a fraction of a number, such as 1/8 of 81, is rooted in the method of cross-multiplication.
Consider the following proportion: (where x represents 1/8 of 81)
- Using the cross-multiplication method, multiply both numerators by their opposite denominators:
- Which gives:
- Divide both sides by 8 to isolate x:
- Which gives the result:
Thus, 1/8 of 81 is equal to 81/8 (or 10.125 in its decimal form).