How to Use the Secret Notes App Built Into Your IPhone’s Calculator
Apple’s big software update in 2024, specifically iOS 18 , iPadOS 18, and macOS 15 Sequoia , added a new tool to the Calculator and Notes apps called Math Notes. It’s essentially a calculation canvas that you can use to develop equations and draw graphs, and if you know how to get the most out of it, it can be incredibly useful.
Whether you’ve encountered Math Notes or not, it’s a good idea to learn about everything it can do, because it’s not immediately obvious what’s possible when you first open it and are faced with a blank screen.
The primary way to access Math Notes is through the Notes app on your iPhone, iPad, or Mac. You can also access it through the Calculator app: tap or click the calculator icon in the bottom left corner, then select Math Notes . You’ll see all your previous math notes listed, with the option to edit them or create new ones.
Simple calculations
The easiest way to get started with Math Notes is to try some simple calculations: If you type something like “4+4” or “8×8” and then add an equal sign, the answer will appear automatically. Press Enter or Spacebar on your keyboard and the calculation will complete.
If you don’t want to use a keyboard, you can also write down your equations if you’re using an iPhone or iPad. Again, all you have to do is put an equals sign and the answer will appear (assuming your text is relatively legible). This gives you more flexibility in terms of the complexity of your equations.
For example, you might jot down long division sums or write down a long column of numbers that need to be added—once you draw a line under them, you’ll get the sum. Math Notes even tries to copy your handwriting so everything looks consistent.
If you see a red line, it means you may have made an error in your equation, while a blue line means clarification is needed. Here’s a fun feature: Click on any handwritten number and a slider will appear on top of it. You can slide your finger left or right on this slider to adjust the number, and the result will also change as you go.
Another neat trick available here is the handling of transformations. If you type “5 m=” or “5 mi=”, Math Notes will understand that you want to see the equivalents in feet and kilometers respectively. This works with a number of different unit types, and if the units you want are not automatically selected, you you can indicate them.
There may be times when you don’t want the results to appear immediately, and you can change this on your iPhone or iPad. Tap the three dots in the top right corner of the note, then select Math Results : This option can be set to Insert Results , Suggest Results, or Off .
Variables and graphs
Math Notes can also handle variables, so letters can replace numbers within your expressions. Setting variables is as simple as adding a line saying “y=100” or “koala=50”, although these lines must appear above the expressions in which they are used.
You can override variables as you work on a note so that they can be configured differently for different expressions. They can also refer to themselves, so something like “y=y+2” will simply increase “y” by two.
When you change any variables, the results of all matching expressions are updated immediately, so you can use variables to update multiple expressions at once, rather than going through them one by one. Variables can also set variables, such as “width x length = area”.
Variables work with the different units of measurement we mentioned earlier, so they can be assigned a value in miles or degrees Fahrenheit, or a price in a specific currency. Math Notes also understands a full set of trigonometric functions, so you can also use “sin”, “cos” and “tan” in your expressions.
On iPhone and iPad, you can also graph your expressions as long as there are two variables on either side of the equal sign. Once you’ve completed the equation, you’ll see a panel pop up with an “Insert Graph” option (if it doesn’t appear right away, try clicking on the equal sign).
Once you’ve created a graph, you’ll see another option for expressions, Add to Existing Graph , so you can combine multiple expressions together. Graphs can be moved and resized within notes, and copied to other applications. Graphs will appear on macOS, but you won’t be able to create them.