4.5 x .34 =

1. Rewrite the problem vertically.  There is no need to line up decimal points.  

          4.5

        X.34 

2. Multiply as if there were no decimal points.

          4.5

        X.34  

         180

       135  

       1.530

3. Count the number of decimal points in both factors.  There must be the same number of decimal points in your product.  See above.