Uploaded January 2016 | Updated September 2026, 2 weeks ago

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This lesson covers least common denominator. Students learn to add or subtract fractions using the least common denominator, which is the least common multiple for the denominators of the fractions. Once the fractions are given a common denominator by multiplying the numerator and denominator of each fraction by the appropriate number, then the fractions can be added or subtracted by adding or subtracting the numerators, and leaving the denominator the same.