You need to know the least common denominator (LCD) of 4 and 72 if you want to add or subtract two fractions with 4 and 72 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 4 and 72 is 72.
Here is a math problem example where you need to know the LCD of 4 and 72 to solve:
3/4 + 2/72 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
72/4 = 18
72/72 = 1
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 18 = 54
2 x 1 = 2
Step 3) Put it all together to solve the problem:
54/72 + 2/72 = 56/72
= 3/4 + 2/72 = 56/72
It's that easy! Once again, the lowest common denominator (LCD) of 4 and 72 is as follows:
72
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