You need to know the least common denominator (LCD) of 99 and 20 if you want to add or subtract two fractions with 99 and 20 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 99 and 20 is 1980.
Here is a math problem example where you need to know the LCD of 99 and 20 to solve:
3/99 + 2/20 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
1980/99 = 20
1980/20 = 99
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 20 = 60
2 x 99 = 198
Step 3) Put it all together to solve the problem:
60/1980 + 198/1980 = 258/1980
= 3/99 + 2/20 = 258/1980
It's that easy! Once again, the lowest common denominator (LCD) of 99 and 20 is as follows:
1980
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