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You find the least common multiple of the denominators [or least common denominator].
Basically, the Least Common Denominator equals the two denominators multiplied together and then divided by any common prime factors. It is easy to see that the numbers 2 and 3 have a common denominator of 6. But the number 4 and 6 do not have a least common denominator of 24, because both numbers are factors of the number 12 (the least number).
Example : add 1/2 and 1/3 -- multiply the numerator and denominator by the same number : (1/2) x (3/3) = 3/6 and (1/3) x (2/2) = 2/6. We are multiplying them by a fraction equal to 1.
Now you can add 3/6 + 2/6 = 5/6
Example : subtract 1/6 from 3/4 -- multiply 1/6 by 2/2 and multiply 3/4 by 3/3
1/6 = 2/12 and 3/4 = 9/12
so 3/4 - 1/6 equals 9/12 - 2/12 = 7/12
If the result is a reducible fraction, reduce it.
What else can I help you with?
When you add or subtract fractions with unlike denominators why do you have to find LCM?
Because to add fractions, the denominators must be equal.
How would you add or subtract fractions with like denominators?
The same way you would add or subtract whole numbers, leaving the denominators alone.
When do you need a common denominator?
The denominators must be the same before you can add or subtract fractions.
Why do you need a common denominator?
Common Denominator means that the denominators in two (or more) fractions are common, or the same. The common denominator is important because before you can add or subtract fractions, the fractions need to have a common denominator.Sometimes fractions have different denominators, like 2/3 and 3/4. If you want to add or subtract them, they need to have the same denominator. In order to do that, you find a common denominator which is the same thing as a common multiple, only with denominators.
Can you explain adding and subtracting fractions with like denominators?
When you add or subtract fractions with like denominators, you just add or subtract the numerators and put them over the same denominator. For example, 3/5 - 2/5 = (3 - 2)/5 = 1/5
