If you use your iPhone as your main calculator, this trick will change your life.

If you don’t—well, it’s still pretty neat, and it’ll probably save you a few seconds every once in a while.  

Granted, it’s not a new feature; it’s been around for a while. It’s just that, while it’s pretty intuitive, it’s not something that you’d figure out during normal use.

If you’re a longtime iPhone user, you know that the most annoying aspect of the calculator app is that it’s unforgiving. There’s no backspace key, so when you make a mistake, you have to start over. If you’ve got a particularly complex equation, this can be maddening, and it can lead to costly mistakes if you’re doing important stuff.

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Here’s the deal: You can backspace, so if you accidentally pressed a number or an operation, you can undo it without starting your equation over.

But there’s no standard backspace button. Instead, you simply have to swipe to the left in the black part of the calculator. A quick swipe will delete a single number; keep swiping to delete the entire sequence. If that doesn’t make it clear, here’s a video showing off the trick.

A Reddit user found this trick, and as word spread, the internet went into a frenzy.

It turns out that this is one of the iPhone’s best-kept secrets. Reactions on Twitter mostly consisted of overjoyed, shocked Apple fans, grateful for the seconds they’d save on their future calculations. Essentially, this is the greatest thing since sliced bread (or at least the sliced bread app, which we’re sure exists).

There’s also a scientific calculator mode.

You might not be aware of this if you keep your Rotation Lock on, but if you’re a student (or if you do complex math problems on a regular basis), it’s incredibly useful. To use it, turn off Rotation Lock, then turn your phone on its side.

Enjoy calculating the sin, cos, tan, rad, and just about anything else.

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Oh, and we’re about to blow your mind one more time: There’s a faster way to charge your iPhone.

Let’s say that you need to head out the door in 20 minutes, and your phone’s battery is at a paltry 15 percent.

Before you plug your iPhone in, put it into Airplane Mode. This turns off the WiFi, Bluetooth, and cell antenna, so your phone won’t be draining while it charges. Granted, it’s not the biggest gain in the world, but it’ll give you about 4 percent more battery life for every 30 minutes.

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Alternately, you can turn your phone completely off, but this is only especially helpful if you’ve got an hour or more to charge the phone, since it’ll use a bit of juice turning on and off.

Anyway, if you do try the Airplane Mode trick, just be sure to remember that your phone’s incapacitated when you head out the door—you’ll definitely want to disable Airplane Mode when you’re actually, you know, waiting for calls and stuff.