Math Notes documentation

Math Notes is an inline calculator that runs entirely in your browser. Type calculations line by line and each result appears beside it as dimmed ghost text, with a running total at the bottom. It is inspired by Numi and Soulver.

This guide covers every feature in depth. Keep it open while you work — it is the long-form reference for the app.

How to read this guide#

Each page focuses on one area and builds from the simple case to the edge cases. Example blocks are real calculations: use Copy to take one away, or Open in Math Notes to try it in the app in a new tab. Nothing you open replaces the sheet you already have.

Everything runs locally. Your sheets are saved in your browser's storage and are never sent to a server.

What Math Notes is not#

It is not a general-purpose programming environment and it is not a spreadsheet. It has one scope per sheet, no cell references by name, and no scripting. Its refusals are deliberate: rather than guess, it reports units that cannot be combined or a tag that has no lines as errors.

• Getting startedMath Notes is a sheet of lines. You write one calculation per line and the answer appears to the right of it as a dimmed hint. There is no = button and no cell grid: the sheet recalculates as you type.
• Writing a sheetA sheet is a list of lines evaluated from top to bottom. Each line can define a value, reference something above it, or simply produce a result. Variables live in one scope per sheet and are available to every line below their definition.
• Numbers & operatorsMath Notes evaluates expressions with the usual arithmetic operators, plus a set of word operators, number scales and rounding phrases that read like English.
• Lists & sequencesLists hold several values. Write one with square brackets, index it, slice it, and use mathjs functions to aggregate or transform it. Lists and ranges are capped at 100 items so a runaway sequence cannot freeze the editor. The cap covers everything that builds a list or matrix (ones, zeros, identity, random, concat, kron, …) and assigning past the end of a list (n[500] = 1).
• Groups & totalsMath Notes aggregates in three related ways: the running total in the bottom bar, the aggregate keywords (sum, average, …) you write on a line, and named groups that show a subtotal in place.
• Units & measuresConvert between units with to, in or as, name what you are measuring to convert across dimensions, and write rates naturally.
• Money & currenciesConvert between currencies using 3-letter ISO codes or symbols. Rates come from the European Central Bank via Frankfurter and are cached locally so conversions keep working offline. While a window stays open the rates are re-checked every hour; if a check fails or takes longer than 10 seconds, the cached rates are used and a short notice says so.
• Dates & timeMath Notes understands calendar dates, clock times and durations. Dates can be written in several styles, stored in variables, and combined with time units.
• Files, sharing & dataMath Notes keeps your work on your device. There is no account and no server: sheets are saved in your browser, backed up in a versioned local store, and shared only when you choose to.
• Settings & appearanceOpen Settings from the footer. Choices are remembered in your browser and applied the next time you open the app.
• App & platformMath Notes is a progressive web app: it installs like a native app, works offline, and respects your system preferences.
• ReferenceA compact reference for the syntax. Every heading links from the sidebar for quick access.
• AboutMath Notes is a browser-based inline calculator, inspired by Numi and Soulver. Its source is open — see the GitHub repository.