You need to know the least common denominator (LCD) of 30 and 9 if you want to add or subtract two fractions with 30 and 9 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 30 and 9 is 90.
Here is a math problem example where you need to know the LCD of 30 and 9 to solve:
3/30 + 2/9 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
90/30 = 3
90/9 = 10
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 3 = 9
2 x 10 = 20
Step 3) Put it all together to solve the problem:
9/90 + 20/90 = 29/90
= 3/30 + 2/9 = 29/90
It's that easy! Once again, the lowest common denominator (LCD) of 30 and 9 is as follows:
90
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