If you don’t already know it, then this tip is about to blow your mind. It’s the paper roll for the Mac’s Calculator app, which has been a feature since, like, forever. You may have been using the Calculator since the very beginnings of Mac OS X, and yet you may still have never seen it.

There’s an old proverb: “The best time to plant a tree is twenty years ago. The second best time is today.” That totally applies to the Mac Calculator’s paper toll. Let’s check it out.

Paper trail

To turn on the paper tape go to Menubar > Window > Show Paper Tape, or hit ⌘-T on the keyboard. Once you have opened up this window, then you can see all your calculations “printed” onto it as you go. One bonus is that the tape keeps recording, even if the window is closed, so you can use the calculator as usual and then open up the paper tape at any time to check your workings.

Here’s the paper tape.

That’s a great tip right there, but while we’re all here with the Calculator app open, lets take a look at some of the other tricks it can do.

Scientific and Programmer calculators

Go to the View menu to switch to the Scientific or Programmer calculator views, or just jump direct to them with the ⌘1, ⌘2, or ⌘3 shortcuts.

Ever wonder what 5FF÷6D is? Now you can find out.

The calculator will also do all manner of conversions, but the interface is so old fashioned that a modal sheet drops down over the main window. You’re much better off doing conversions using Spotlight.

So, there you have it. The Mac is like the depths of the Earth’s oceans. We might be looking to spend billions on sending electric cars to Mars, but the mysteries of the deep are just unexplored as the far reaches of our Solar System.