Soon the formerly illicit item would be replaced with the all mighty 'scientific calcalutor' - it was bigger, had three times the buttons ... calcuator is back in common use as an app on billions ...

One user highlighted the importance of this knowledge in the 'You Should Know' forum, commenting: "These buttons actually do different things and it can help you use a calculator more effectively." ...

And sure, you can't use it in any exam hall, but it's still pretty neat. If you're not a calculator whiz, you might not understand exactly how the C or "clear" button works. When you tap it ...