You need to know the least common denominator (LCD) of 5 and 81 if you want to add or subtract two fractions with 5 and 81 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 5 and 81 is 405.
Here is a math problem example where you need to know the LCD of 5 and 81 to solve:
3/5 + 2/81 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
405/5 = 81
405/81 = 5
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 81 = 243
2 x 5 = 10
Step 3) Put it all together to solve the problem:
243/405 + 10/405 = 253/405
= 3/5 + 2/81 = 253/405
It's that easy! Once again, the lowest common denominator (LCD) of 5 and 81 is as follows:
405
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