What is 7/8 of 18?
Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 7/8 of 18? We'll show you a straightforward method to achieve that.
How to calculate 7/8 of 18?
- Multiply the whole number by the numerator of the fraction: 18 × 7 = 126
- Divide this result by denominator of the fraction: 126/8 = 15.75
- Simplify by dividing both the numerator and denominator by their GCD (2):
- 126/2 = 63
- 8/2 = 4
- Which gives: 63/4
Since 63/4 is an improper fraction, the result could also be expressed as a mixed number: 15 3/4
How does it work?
The principle behind finding a fraction of a number, such as 7/8 of 18, is rooted in the method of cross-multiplication.
Consider the following proportion: (where x represents 7/8 of 18)
- 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: (or )
Thus, 7/8 of 18 is equal to 63/4 (or 15.75 in its decimal form).