You need to know the least common denominator (LCD) of 9 and 42 if you want to add or subtract two fractions with 9 and 42 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 9 and 42 is 126.
Here is a math problem example where you need to know the LCD of 9 and 42 to solve:
3/9 + 2/42 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
126/9 = 14
126/42 = 3
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 14 = 42
2 x 3 = 6
Step 3) Put it all together to solve the problem:
42/126 + 6/126 = 48/126
= 3/9 + 2/42 = 48/126
It's that easy! Once again, the lowest common denominator (LCD) of 9 and 42 is as follows:
126
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