You need to know the least common denominator (LCD) of 4 and 42 if you want to add or subtract two fractions with 4 and 42 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 4 and 42 is 84.
Here is a math problem example where you need to know the LCD of 4 and 42 to solve:
3/4 + 2/42 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
84/4 = 21
84/42 = 2
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 21 = 63
2 x 2 = 4
Step 3) Put it all together to solve the problem:
63/84 + 4/84 = 67/84
= 3/4 + 2/42 = 67/84
It's that easy! Once again, the lowest common denominator (LCD) of 4 and 42 is as follows:
84
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