You need to know the least common denominator (LCD) of 12 and 7 if you want to add or subtract two fractions with 12 and 7 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 12 and 7 is 84.
Here is a math problem example where you need to know the LCD of 12 and 7 to solve:
3/12 + 2/7 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
84/12 = 7
84/7 = 12
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 7 = 21
2 x 12 = 24
Step 3) Put it all together to solve the problem:
21/84 + 24/84 = 45/84
= 3/12 + 2/7 = 45/84
It's that easy! Once again, the lowest common denominator (LCD) of 12 and 7 is as follows:
84
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