What is 9/10 of 87?
Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 9/10 of 87? We'll show you a straightforward method to achieve that.
How to calculate 9/10 of 87?
- Multiply the whole number by the numerator of the fraction: 87 × 9 = 783
- Divide this result by denominator of the fraction: 783/10 = 78.3
Since 783/10 is an improper fraction, the result could also be expressed as a mixed number: 78 3/10
How does it work?
The principle behind finding a fraction of a number, such as 9/10 of 87, is rooted in the method of cross-multiplication.
Consider the following proportion: (where x represents 9/10 of 87)
- Using the cross-multiplication method, multiply both numerators by their opposite denominators:
- Which gives:
- Divide both sides by 10 to isolate x:
- Which gives the result:
Thus, 9/10 of 87 is equal to 783/10 (or 78.3 in its decimal form).