Multiplying Fractions
Multiplying Fractions
Basic Concept
To multiply fractions, you multiply the numerators together to get the new numerator, and you multiply the denominators together to get the new denominator.
- For example: \frac{a}{b} \times \frac{c}{d} = \frac{a \times c}{b \times d}
Example 1
Problem: \frac{1}{2} \times \frac{3}{4}
Step 1: Multiply the numerators: 1 \times 3 = 3
Step 2: Multiply the denominators: 2 \times 4 = 8
Solution: \frac{1}{2} \times \frac{3}{4} = \frac{3}{8}
Example 2
Problem: \frac{2}{5} \times \frac{7}{9}
Step 1: Multiply the numerators: 2 \times 7 = 14
Step 2: Multiply the denominators: 5 \times 9 = 45
Solution: \frac{2}{5} \times \frac{7}{9} = \frac{14}{45}
Example 3
Problem: \frac{4}{6} \times \frac{2}{3}
Step 1: Multiply the numerators: 4 \times 2 = 8
Step 2: Multiply the denominators: 6 \times 3 = 18
Initial Solution: \frac{8}{18}
Step 3: Simplify the fraction (if possible).
Find a common factor for both the numerator and the denominator. In this case, both 8 and 18 are divisible by 2.
Divide both the numerator and the denominator by the common factor: \frac{8 \div 2}{18 \div 2} = \frac{4}{9}
Simplified Solution: \frac{4}{9}
Simplifying Before Multiplying (Optional)
Sometimes, it’s easier to simplify before multiplying.
Example: \frac{4}{6} \times \frac{2}{3} can be simplified by noticing that 4 and 2 share a common factor with 6 and 3 respectively.
Simplify \frac{4}{6} to \frac{2}{3} by dividing both by 2.
The problem becomes: \frac{2}{3} \times \frac{2}{3}
Multiply the numerators: 2 \times 2 = 4
Multiply the denominators: 3 \times 3 = 9
Solution: \frac{4}{9} (Same as simplifying after multiplying)
Multiplying More Than Two Fractions
The same principle applies when multiplying more than two fractions.
Example: \frac{1}{2} \times \frac{2}{3} \times \frac{3}{4}
Multiply all numerators: 1 \times 2 \times 3 = 6
Multiply all denominators: 2 \times 3 \times 4 = 24
Initial Solution: \frac{6}{24}
Simplify the fraction by dividing both numerator and denominator by their greatest common divisor, which is 6.
Simplified Solution: \frac{6 \div 6}{24 \div 6} = \frac{1}{4}
Key Points
Always multiply numerators together and denominators together.
Simplify the fraction after multiplying, if possible, to get the answer in its simplest form.
Simplifying before multiplying can make the calculation easier.