SQL & PL/SQL

Please Help!!!!

I was wondering if anyone knew of a wildcard to look at only numeric. For example...

'Not like 4%' is a statement that only looks at 4... numbers. This will bring back 4100 numbers and 4X10 number which we have both of, but I want only the 4100
numbers.
But what I want it to do is have two spaces with a wildcard that will look and make sure they are numeric. The only two wildcards I know are _ (underscore) and %
(percent sign). Both of
these wildcards look at both charector and numeric. I don't know if I explained this well enough, so let me know.

Thanks
Shelby