You need to know the least common denominator (LCD) of 9 and 91 if you want to add or subtract two fractions with 9 and 91 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 9 and 91 is 819.
Here is a math problem example where you need to know the LCD of 9 and 91 to solve:
3/9 + 2/91 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
819/9 = 91
819/91 = 9
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 91 = 273
2 x 9 = 18
Step 3) Put it all together to solve the problem:
273/819 + 18/819 = 291/819
= 3/9 + 2/91 = 291/819
It's that easy! Once again, the lowest common denominator (LCD) of 9 and 91 is as follows:
819
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