You need to know the least common denominator (LCD) of 9 and 90 if you want to add or subtract two fractions with 9 and 90 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 9 and 90 is 90.
Here is a math problem example where you need to know the LCD of 9 and 90 to solve:
3/9 + 2/90 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
90/9 = 10
90/90 = 1
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 10 = 30
2 x 1 = 2
Step 3) Put it all together to solve the problem:
30/90 + 2/90 = 32/90
= 3/9 + 2/90 = 32/90
It's that easy! Once again, the lowest common denominator (LCD) of 9 and 90 is as follows:
90
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