Well if you think about it, a common denominator is a denominator that is the same when you are adding or subtracting fractions. A common multiple is a multiple of two or more numbers. Such as saying you use a common denominator when you are adding or subtracting fractions. To get a common denominator, you would have to use a common multiple. Let's try this:
Steps:
1. You need to find a number that 4 and 6 have in common.
2. You multiply the numerator by the number that you multiplied for the denominator
3. Add the numerators
(but not the denominators!!!!)4. Simplify if needed.
Hope that helped!