What do you do if the bottom numbers are different in fractions?

Answer 1

Those "bottom" numbers are called denominators. It just depends what kind of operation (add, subtract, multiply, divide) you are asked to perform with these fractions.

In this case, I am going to assume that you are asked to add or subtract fractions with different denominators (bottom numbers). (In any other case, such as multiplying or dividing, the denominators need not be the same.) If this is the case, then you are going to have to find a common denominator. This can be done by finding the LCM (least common multiple) of both denominators.

Example: (1/3) + (1/2) = ?

Since the denominators (3 and 2) are different, you will need to find the LCM. In this case, the LCM of 3 and 2 is 6. Now, in order to make the denominators the same, you will need to multiply the 3 by 2 and the 2 by 3 to get a common denominator of 6. Now, remember that what you are doing is simply "renaming" the fraction. So, what you do to the denominator (bottom number), you must also do to the numerator (top number). You can think of it as multiplying both fractions by a fancy form of 1...which as you should know, anything times 1 is just that same number. So, multiply the first fraction by 2/2 and the second fraction by 3/3)

Now you get {(1/3)*(2/2)} + {(1/2)*(3/3)} = (2/6) + (3/6) = (5/6)

Hope this helps! :)