You have to buy one if you want one at my school, and really the only think you can use it for is to get the Student Discount at the movie theater in a neighboring town.
They also issue us numbers for lunch and stuff.
If you want to put money in your account for lunch instead of bringing money everyday, you bring a check one day and they put the money in your account. The next time you buy your lunch you put your number in and they deduct however much from your account.
And we use the numbers for passwords for quizzes we take that are on the computer.
And we need the number to check out a library book.
They also use it for certain administrative things.
We've had these numbers since like second grade, when we had to use them for every thing.