Projects that don't exactly have a practical value for me, but that I wanted to build. I have a thing for information hidden in plain sight...
In this educational script, a user enters an interstate number and receives information about that interstate. All the information is derived solely from the number, based on the naming conventions of the Interstate Highway System.
This script uses the check digit built into an ISBN to check whether a user inputted ISBN is potentially valid. It's compatible with both ISBN-10 and ISBN-13. If the user inputs the first 9 or 12 digits of an ISBN, the final check digit is provided.