Multiplying and Dividing Fractions — Reciprocals Made Easy
Multiplying and dividing fractions follow simple rules — simpler than addition and subtraction since no common denominator is needed!
Multiplying Fractions
**Rule:** Numerator times numerator, denominator times denominator.
**Example:** 2/3 × 4/5 = (2 × 4) / (3 × 5) = 8/15.
**Tip:** You can cross-cancel before multiplying: with 3/4 × 2/9, cancel the 3 and 9 (by 3) and the 2 and 4 (by 2): 1/2 × 1/3 = 1/6.
Multiplying a Fraction by a Whole Number
Write the whole number as a fraction with denominator 1: 3/4 × 5 = 3/4 × 5/1 = 15/4 = 3 3/4.
What Is the Reciprocal?
The reciprocal of a fraction is created by swapping numerator and denominator. The reciprocal of 3/4 is 4/3. The reciprocal of 5 (= 5/1) is 1/5. Important: 0 has no reciprocal!
Dividing Fractions
**Rule:** Multiply by the reciprocal of the second fraction.
**Example:** 2/3 ÷ 4/5 = 2/3 × 5/4 = 10/12 = 5/6.
**Why does this work?** Division is the inverse operation of multiplication. 'Dividing by 4/5' is the same as 'multiplying by 5/4'.
Common Mistakes
1. Forgetting to take the reciprocal when dividing.
2. Flipping both fractions instead of just the second one.
3. Not simplifying the result.
Multiplying/Dividing Mixed Numbers
Convert mixed numbers to improper fractions first: 1 1/2 × 2 1/3 = 3/2 × 7/3 = 21/6 = 7/2 = 3 1/2.
Our Fraction Calculator
In the 'Basic Operations' tab, you can calculate multiplication and division instantly. Switch between +, -, × and ÷ with one click!
