You need to know the least common denominator (LCD) of 8 and 18 if you want to add or subtract two fractions with 8 and 18 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 8 and 18 is 72.
Here is a math problem example where you need to know the LCD of 8 and 18 to solve:
3/8 + 2/18 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
72/8 = 9
72/18 = 4
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 9 = 27
2 x 4 = 8
Step 3) Put it all together to solve the problem:
27/72 + 8/72 = 35/72
= 3/8 + 2/18 = 35/72
It's that easy! Once again, the lowest common denominator (LCD) of 8 and 18 is as follows:
72
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