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.