perform a calculation on the number part of the string

If in A1 there is a code say 1234M can I get another cell to perform a calculation on the number part of the code? And how could I make it so if there are two or more possible calculations that can be performed depending on the Letter, the correct one is performed. Thanks!

Many thanks for that, those are the calculations I require. I have to integrate that into an existing spreadsheet some how so I may be asking more questions!