What is 4/10 of 85?
Often, in mathematics or everyday life, we need to find a fraction of a given number. For instance, how would you quickly calculate 4/10 of 85? We'll show you a straightforward method to achieve that.
How to calculate 4/10 of 85?
- Multiply the whole number by the numerator of the fraction: 85 × 4 = 340
- Divide this result by denominator of the fraction: 340/10 = 34
- Simplify by dividing both the numerator and denominator by their GCD (10):
- 340/10 = 34
- 10/10 = 1
- Which gives: 34/1
How does it work?
The principle behind finding a fraction of a number, such as 4/10 of 85, is rooted in the method of cross-multiplication.
Consider the following proportion: (where x represents 4/10 of 85)
- 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: (or )
Thus, 4/10 of 85 is equal to 34/1 (or 34 in its decimal form).