Maybe you’ve been there: You’re using your iPhone’s calculator to solve a sophisticated math equation (or calculate the tip on your dinner bill) when your thumb hits the wrong key. If you’re like many iPhone owners, your first instinct may be to hit “C” and start over from scratch. But as The Next Web reports, there’s a better way.

On May 2, Twitter user CENSORED Dialogue revealed a trick that, based on the viral response, is a game-changer for many people with iPhones. The video below demonstrates how deleting numbers one digit at a time in the calculator app can be done by swiping a finger across the numbers themselves. One horizontal swipe to the left or the right acts as a backspace button for the most recent digit, another swipe removes the digit before that, and so on.

The feature has been a part of the calculator app for at least five years, but unless you knew about it already or discovered it accidentally it’s easy to miss. iPhone users may also be surprised to learn of other hidden tricks that could improve the way they text, email, and conserve battery life. Follow the Apple Support Twitter page to keep tabs on any features you may not be taking advantage of.

[h/t The Next Web]