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: ab×cd=a×cb×d\frac{a}{b} \times \frac{c}{d} = \frac{a \times c}{b \times d}$$\frac{a}{b} \times \frac{c}{d} = \frac{a \times c}{b \times d}$$

Example 1

  • Problem: 12×34\frac{1}{2} \times \frac{3}{4}$$\frac{1}{2} \times \frac{3}{4}$$

  • Step 1: Multiply the numerators: 1×3=31 \times 3 = 3$$1 \times 3 = 3$$

  • Step 2: Multiply the denominators: 2×4=82 \times 4 = 8$$2 \times 4 = 8$$

  • Solution: 12×34=38\frac{1}{2} \times \frac{3}{4} = \frac{3}{8}$$\frac{1}{2} \times \frac{3}{4} = \frac{3}{8}$$

Example 2

  • Problem: 25×79\frac{2}{5} \times \frac{7}{9}$$\frac{2}{5} \times \frac{7}{9}$$

  • Step 1: Multiply the numerators: 2×7=142 \times 7 = 14$$2 \times 7 = 14$$

  • Step 2: Multiply the denominators: 5×9=455 \times 9 = 45$$5 \times 9 = 45$$

  • Solution: 25×79=1445\frac{2}{5} \times \frac{7}{9} = \frac{14}{45}$$\frac{2}{5} \times \frac{7}{9} = \frac{14}{45}$$

Example 3

  • Problem: 46×23\frac{4}{6} \times \frac{2}{3}$$\frac{4}{6} \times \frac{2}{3}$$

  • Step 1: Multiply the numerators: 4×2=84 \times 2 = 8$$4 \times 2 = 8$$

  • Step 2: Multiply the denominators: 6×3=186 \times 3 = 18$$6 \times 3 = 18$$

  • Initial Solution: 818\frac{8}{18}$$\frac{8}{18}$$

  • 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: 8÷218÷2=49\frac{8 \div 2}{18 \div 2} = \frac{4}{9}$$\frac{8 \div 2}{18 \div 2} = \frac{4}{9}$$

  • Simplified Solution: 49\frac{4}{9}$$\frac{4}{9}$$

Simplifying Before Multiplying (Optional)

  • Sometimes, it’s easier to simplify before multiplying.

  • Example: 46×23\frac{4}{6} \times \frac{2}{3}$$\frac{4}{6} \times \frac{2}{3}$$ can be simplified by noticing that 4 and 2 share a common factor with 6 and 3 respectively.

  • Simplify 46\frac{4}{6}$$\frac{4}{6}$$ to 23\frac{2}{3}$$\frac{2}{3}$$ by dividing both by 2.

  • The problem becomes: 23×23\frac{2}{3} \times \frac{2}{3}$$\frac{2}{3} \times \frac{2}{3}$$

  • Multiply the numerators: 2×2=42 \times 2 = 4$$2 \times 2 = 4$$

  • Multiply the denominators: 3×3=93 \times 3 = 9$$3 \times 3 = 9$$

  • Solution: 49\frac{4}{9}$$\frac{4}{9}$$ (Same as simplifying after multiplying)

Multiplying More Than Two Fractions

  • The same principle applies when multiplying more than two fractions.

  • Example: 12×23×34\frac{1}{2} \times \frac{2}{3} \times \frac{3}{4}$$\frac{1}{2} \times \frac{2}{3} \times \frac{3}{4}$$

  • Multiply all numerators: 1×2×3=61 \times 2 \times 3 = 6$$1 \times 2 \times 3 = 6$$

  • Multiply all denominators: 2×3×4=242 \times 3 \times 4 = 24$$2 \times 3 \times 4 = 24$$

  • Initial Solution: 624\frac{6}{24}$$\frac{6}{24}$$

  • Simplify the fraction by dividing both numerator and denominator by their greatest common divisor, which is 6.

  • Simplified Solution: 6÷624÷6=14\frac{6 \div 6}{24 \div 6} = \frac{1}{4}$$\frac{6 \div 6}{24 \div 6} = \frac{1}{4}$$

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.


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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: ab×cd=a×cb×d\frac{a}{b} \times \frac{c}{d} = \frac{a \times c}{b \times d}

Example 1

  • Problem: 12×34\frac{1}{2} \times \frac{3}{4}

  • Step 1: Multiply the numerators: 1×3=31 \times 3 = 3

  • Step 2: Multiply the denominators: 2×4=82 \times 4 = 8

  • Solution: 12×34=38\frac{1}{2} \times \frac{3}{4} = \frac{3}{8}

Example 2

  • Problem: 25×79\frac{2}{5} \times \frac{7}{9}

  • Step 1: Multiply the numerators: 2×7=142 \times 7 = 14

  • Step 2: Multiply the denominators: 5×9=455 \times 9 = 45

  • Solution: 25×79=1445\frac{2}{5} \times \frac{7}{9} = \frac{14}{45}

Example 3

  • Problem: 46×23\frac{4}{6} \times \frac{2}{3}

  • Step 1: Multiply the numerators: 4×2=84 \times 2 = 8

  • Step 2: Multiply the denominators: 6×3=186 \times 3 = 18

  • Initial Solution: 818\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: 8÷218÷2=49\frac{8 \div 2}{18 \div 2} = \frac{4}{9}

  • Simplified Solution: 49\frac{4}{9}

Simplifying Before Multiplying (Optional)

  • Sometimes, it’s easier to simplify before multiplying.

  • Example: 46×23\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 46\frac{4}{6} to 23\frac{2}{3} by dividing both by 2.

  • The problem becomes: 23×23\frac{2}{3} \times \frac{2}{3}

  • Multiply the numerators: 2×2=42 \times 2 = 4

  • Multiply the denominators: 3×3=93 \times 3 = 9

  • Solution: 49\frac{4}{9} (Same as simplifying after multiplying)

Multiplying More Than Two Fractions

  • The same principle applies when multiplying more than two fractions.

  • Example: 12×23×34\frac{1}{2} \times \frac{2}{3} \times \frac{3}{4}

  • Multiply all numerators: 1×2×3=61 \times 2 \times 3 = 6

  • Multiply all denominators: 2×3×4=242 \times 3 \times 4 = 24

  • Initial Solution: 624\frac{6}{24}

  • Simplify the fraction by dividing both numerator and denominator by their greatest common divisor, which is 6.

  • Simplified Solution: 6÷624÷6=14\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.