how to change 1/2 into a whole number

Courtney, you must have misunderstood your teacher, at least a little.

1/3 is never equal to 3 or any other whole number. However, it is equal to 0.33333... with the 3 repeated forever.

In the same way, 1/2 is never equal to a whole number. It is equal to 0.5, which has a decimal but not a fraction. You could multiply by 0.5 the same way you multiply by 5, except that you might have at least one extra decimal place in the answer.

Example: Suppose you want to multiply 16 by 1/2.  Change the 1/2 to 0.5 and set it up this way:

             16
          X 0.5
____________
             8.0  (or just 8)

Any fraction can be changed into a decimal by dividing the denominator into the numerator and carrying it out as many places as you wish. Just remember to keep track of where the decimal point should be.

You can make any fraction into a whole number by multiplying the fraction by the same number in the denominator.  For example, if you multiply 1/3 by 3, you get 1; if you multiply 1/2 by 2, you get 1; if you multiply 2/3 by 3, you would get 2.

I think, though, that what you probably want to know is how to convert a fraction into a decimal.  If that is the case, I think the easiest way to do it is to just divide the numerator by the denominator.  For example 1/2 is the same as 1 divided by 2, which is 0.5; and 1/3 is 1 divided by 3, which is 0.3333333 (the 3 repeats indefinitely).

      0 . 3 3 3

    ____________

3  ) 1 . 0 0 0

           9

      ____

           1 0

              9

          ____

              1 0

                 9

... (etc.)