How to get the first 2 numbers

[Anon]

I would like to know how do i get the first two numbers from this :

S8130045J
I only want to take out 81
Can someone please tell me how this can be done.
Thank You.

[Anon]

It depends on a few things:
If the string is allways in the format a0000000a
then you could simply use a substring.
If there can be more than 1 letter at the beginning,
you might want to use a regular expression to match
1+ strings, then 2 numbers, then 1+ numbers, then 1+ strings.

You can make regular expressions so that they put the 'match' into a variable.
Check out the manual because it can be tricky to do.