Yes, Perl can do calculations. Perl has all the standard mathematical operators; + (plus), - (minus), * (times), / (divide), and so on.

If you want it to calculate PI to 300 digits, Perl is there for you too, but you've got to learn to program. A good place to start learning Perl is to read "Learning Perl", published by O'Reilly & Associates. You'll find it in most larger bookstores, as well as Amazon.