You need to know the least common denominator (LCD) of 8 and 20 if you want to add or subtract two fractions with 8 and 20 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 8 and 20 is 40.
Here is a math problem example where you need to know the LCD of 8 and 20 to solve:
3/8 + 2/20 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
40/8 = 5
40/20 = 2
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 5 = 15
2 x 2 = 4
Step 3) Put it all together to solve the problem:
15/40 + 4/40 = 19/40
= 3/8 + 2/20 = 19/40
It's that easy! Once again, the lowest common denominator (LCD) of 8 and 20 is as follows:
40
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