Example: 7/30 + 5/42
Find the LCD by factoring them.
2 x 3 x 5 = 30
2 x 3 x 7 = 42
2 x 3 x 5 x 7 = 210, the LCD
30 x 7 = 210
42 x 5 = 210
7/30 x 7/7 = 49/210
5/42 x 5/5 = 25/210
49/210 + 25/210 = 74/210
Simplify if necessary.
7/30 + 5/42 = 37/105
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If the denominators are not the same, then you have to use equivalent fractions which do have a common denominator . To do this, you need to find the least common multiple (LCM) of the two denominators.
Common Denominator means that the denominators in two (or more) fractions are common, or the same. The common denominator is important because before you can add or subtract fractions, the fractions need to have a common denominator.Sometimes fractions have different denominators, like 2/3 and 3/4. If you want to add or subtract them, they need to have the same denominator. In order to do that, you find a common denominator which is the same thing as a common multiple, only with denominators.
Find the lowest common multiple of the denominators and adjust the fractions accordingly
Exactly the same as you do when multiplying fractions with different denominators. -- Multiply numerators . . . the product is the numeratore of the answer. -- Multiply denominators . . . the product is the denominator of the answer.
YES.