Fraction Rules

Adding and Subtracting

Find a common denominator. 3/4 + 1/6: LCM of 4 and 6 = 12. Convert: 9/12 + 2/12 = 11/12. For subtraction, same process with minus: 9/12 − 2/12 = 7/12.

Multiplying and Dividing

Multiply: numerator × numerator, denominator × denominator. 3/4 × 2/5 = 6/20 = 3/10. Divide: multiply by the reciprocal. 3/4 ÷ 2/5 = 3/4 × 5/2 = 15/8 = 1 and 7/8.

Simplifying

Divide both numerator and denominator by their GCD. 15/20: GCD = 5, so 15/20 = 3/4. A fraction is fully simplified when the GCD of numerator and denominator is 1.

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