convert string to number

[wxdqz]

I have string in the form "setuppage,234"

This gets converted to an array like so

str[0]=setuppage
str[1]=234

and str[1] gets stored in another variable pagenum

so that pagenum=234

I want to add a number to the variable ie.

finalpage=pagenum+5

but instead of getting 239, I get 2345

How can I convert pagenum to a number?

Thanks

Goose