A Challenge for you all, I desperately need help.

I would like code that will manipulate a number upon entry
into a text box.

When entering a number eg 487654321 and pressing enter, it
checks the 1st digit, and depending on the digit replces
it with a number, i.e a 4 is a D/, a 8 is a A/. But if the
first digit is a 7 it keeps it as a 7/. Basically the
ability for me to define what the first digit will be
replaced with.

It also checks the last digit and puts a dash before it so
ending in 1 becomes -1, ending in 4 becomes -4 apart from
when it ends in * then I want it to become -10.

A few examples

4123456789 --- D/12345678-9
412345678* --- D/12345678-10
8876543210 --- A/87654321-0
7232323232 --- 7/23232323-2

Hope someone is bright enough to help

Thanks

Dean Knox