You need to know the least common denominator (LCD) of 91 and 20 if you want to add or subtract two fractions with 91 and 20 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 91 and 20 is 1820.
Here is a math problem example where you need to know the LCD of 91 and 20 to solve:
3/91 + 2/20 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
1820/91 = 20
1820/20 = 91
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 20 = 60
2 x 91 = 182
Step 3) Put it all together to solve the problem:
60/1820 + 182/1820 = 242/1820
= 3/91 + 2/20 = 242/1820
It's that easy! Once again, the lowest common denominator (LCD) of 91 and 20 is as follows:
1820
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