Bugs

The program should be:

' Computing 12 times 12
PRINT "The square of 12 is", 12*12
END

If you try to run the incorrect version you get a message window on your computer screen that lists the problem. (Often the message is hard to understand. Some syntax errors confuse the QBasic system so badly it does not know what to do.) Hopefully you can figure out the syntax error, correct it, and run the program.

Programs can have errors other than syntax errors. Just as you can say something in grammatical English that is incorrect, you can write a program in QBasic that has no syntax errors but computes an incorrect result. Such a program has one or more bugs.