LabVIEW has a free 30-day evaluation copy you can download at National Instruments or you can purchase the LabVIEW 2009 Student Edition
Once you install LabVIEW on your computer, you can go through the "Getting Started with LabVIEW" tutorials which help you get familiar with the inner workings of LabVIEW. You can learn how to convert degrees C to F by using only mathematical terms and the front panel controls. I've seen on YouTube video on building a calculator using LabVIEW. It's a bit long and tedious to build but it's a valuable learning experience if you work through it.