Once you extract "A", search for the decimal, then move the characters to the right of the decimal into another string, String-1. Move the characters to the left of the decimal to yet another string, String-2. Use the string to integer instruction to convert String-1 to an integer, then move String-2 to another integer. Divide String-2 by the number places to the left of the decimal. That is if you have 3, divide by 1000, for 2 divide by 100, store this in a Floating point, the add the interger from String-1, store the results in a Floating point.
It's a very drawn out method, and will require a lot of ladder coding, but it can be done.