You need to know the least common denominator (LCD) of 3 and 5 if you want to add or subtract two fractions with 3 and 5 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 3 and 5 is 15.
Here is a math problem example where you need to know the LCD of 3 and 5 to solve:
3/3 + 2/5 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
15/3 = 5
15/5 = 3
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 5 = 15
2 x 3 = 6
Step 3) Put it all together to solve the problem:
15/15 + 6/15 = 21/15
= 3/3 + 2/5 = 21/15
It's that easy! Once again, the lowest common denominator (LCD) of 3 and 5 is as follows:
15
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