It just so happens I'm making a calculator for Visual Basic class. (Don't laugh. There's only two programming classes available at my college.) I don't have the source with me though to show you. But I'll try to explain it. I'm making an RPN calculator. I have a boolean variable called reset. Whenever the user clicks a number, if reset is true or the display is "0", then the display changes to that number. In other cases, the number is appended to the display. Any time a number is pressed, reset is cleared. Whenever a function or enter is pressed, reset is set. I figure you can do basically the same thing with a standard calculator. If you want to do it like a TI, I can't help you.