You need to know the least common denominator (LCD) of 18 and 8 if you want to add or subtract two fractions with 18 and 8 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 18 and 8 is 72.
Here is a math problem example where you need to know the LCD of 18 and 8 to solve:
3/18 + 2/8 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
72/18 = 4
72/8 = 9
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 4 = 12
2 x 9 = 18
Step 3) Put it all together to solve the problem:
12/72 + 18/72 = 30/72
= 3/18 + 2/8 = 30/72
It's that easy! Once again, the lowest common denominator (LCD) of 18 and 8 is as follows:
72
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