Pulling numbers from ASCII filename not working

[IamIan]

The exception I get is "TypeError: Cannot add value 'int' to string." I
have looked at LatString, and it is the string representation of
latitude ('17' etc.). What's odd is that the exception is raised not
when I include LatInt = int(LatString), but when I try to print
LatInt's value or multiply it by another number.

Filenames are along the lines of "N16W110.asc" - is there another way
to get LatString into a number for multiplication purposes?