Example: 1/30 and 1/42
Factor the denominators.
2 x 3 x 5 = 30
2 x 3 x 7 = 42
Combine the factors, eliminating duplicates.
2 x 3 x 5 x 7 = 210, the LCD
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You need at least two numbers to find a common denominator.
You need at least two denominators to find an LCD.
You need at least two numbers to find something in common.
You need at least two denominators to find something in common between them. If that's 3 and 2, the common denominator is 6..
First you find a common multiple of the denominators. The least common denominator is handy but not essential. This number will be the denominator of the answer - before simplification.For both fractions find an equivalent fraction whose denominator is this common denominator.Carry out the subtraction on the new numerators to give the numerator of the answer.Simplify the result for the final, simplified answer.First you find a common multiple of the denominators. The least common denominator is handy but not essential. This number will be the denominator of the answer - before simplification.For both fractions find an equivalent fraction whose denominator is this common denominator.Carry out the subtraction on the new numerators to give the numerator of the answer.Simplify the result for the final, simplified answer.First you find a common multiple of the denominators. The least common denominator is handy but not essential. This number will be the denominator of the answer - before simplification.For both fractions find an equivalent fraction whose denominator is this common denominator.Carry out the subtraction on the new numerators to give the numerator of the answer.Simplify the result for the final, simplified answer.First you find a common multiple of the denominators. The least common denominator is handy but not essential. This number will be the denominator of the answer - before simplification.For both fractions find an equivalent fraction whose denominator is this common denominator.Carry out the subtraction on the new numerators to give the numerator of the answer.Simplify the result for the final, simplified answer.