You need to know the least common denominator (LCD) of 5 and 4 if you want to add or subtract two fractions with 5 and 4 as denominators.
The least common denominator, also called lowest common denominator (LCD), of 5 and 4 is 20.
Here is a math problem example where you need to know the LCD of 5 and 4 to solve:
3/5 + 2/4 = ?
Step 1) Take the LCD and divide each denominator by it as follows:
20/5 = 4
20/4 = 5
Step 2) Multiply each nominator with the respective answers from Step 1:
3 x 4 = 12
2 x 5 = 10
Step 3) Put it all together to solve the problem:
12/20 + 10/20 = 22/20
= 3/5 + 2/4 = 22/20
It's that easy! Once again, the lowest common denominator (LCD) of 5 and 4 is as follows:
20
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