You need to know the least common denominator (LCD) of 28 and 39 if you want to add or subtract two fractions with 28 and 39 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 28 and 39 is 1092.
Here is a math problem example where you need to know the LCD of 28 and 39 to solve:
3/28 + 2/39 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
1092/28 = 39
1092/39 = 28
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 39 = 117
2 x 28 = 56
Step 3) Put it all together to solve the problem:
117/1092 + 56/1092 = 173/1092
= 3/28 + 2/39 = 173/1092
It's that easy! Once again, the lowest common denominator (LCD) of 28 and 39 is as follows:
1092
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