You need to know the least common denominator (LCD) of 13 and 90 if you want to add or subtract two fractions with 13 and 90 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 13 and 90 is 1170.
Here is a math problem example where you need to know the LCD of 13 and 90 to solve:
3/13 + 2/90 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
1170/13 = 90
1170/90 = 13
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 90 = 270
2 x 13 = 26
Step 3) Put it all together to solve the problem:
270/1170 + 26/1170 = 296/1170
= 3/13 + 2/90 = 296/1170
It's that easy! Once again, the lowest common denominator (LCD) of 13 and 90 is as follows:
1170
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