Operating with Fractions

Addition/Subtraction

Same denominator: Add/subtract numerators

• $\frac{2}{5} + \frac{1}{5} = \frac{3}{5}$

Different denominators: Find LCD (Least Common Denominator)

• $\frac{1}{4} + \frac{1}{3} = \frac{3}{12} + \frac{4}{12} = \frac{7}{12}$

Multiplication

Multiply numerators, multiply denominators

• $\frac{2}{3} \times \frac{3}{4} = \frac{6}{12} = \frac{1}{2}$

Division

Multiply by the reciprocal (flip second fraction)

• $\frac{2}{3} \div \frac{1}{4} = \frac{2}{3} \times \frac{4}{1} = \frac{8}{3}$

Decimal Operations

Add/subtract: Line up decimal points Multiply: Ignore decimals, then count places Divide: Move decimal in divisor to make whole number