Start Here — A Complete Tour
Start here. One live worksheet that shows every feature — variables, units, plots, diagrams, sums, matrices, and the solvers — and how to use each.
Welcome. This worksheet is a working tour of everything NapkinCalc can do — and it is itself a live document. Every number with a grey result beside it is a real engine evaluation, not a screenshot. Change any value and the whole sheet recomputes instantly. Read top to bottom, poke at the numbers as you go, and by the end you will know the whole tool.
Tip: this is your own copy — edit freely. Add a cell with the + button (or the toolbar), delete one from its cell menu (the ⋮ that appears on hover), and undo anything with Ctrl/⌘ + Z.
- 01 Defining values — the := assignment The one move you will make most: name := value. The name on the left becomes a variable you can reuse anywhere below; the result shows to the right. Type := as…
- 02 Units are first-class Numbers can carry units, and NapkinCalc tracks them through every calculation — multiplying, dividing, and converting automatically. A unit mismatch (adding…
- 03 Names, subscripts & arrays Two naming ideas worth knowing early: Subscripts are part of the name. Type v_max (a letter, underscore, then more) and you get the single variable v-max — not…
- 04 Checks — let the sheet prove itself A check is a statement you claim is true. The engine evaluates it and shows a green tick when it holds, a red mark when it does not — so your worksheet can…
- 05 Plots — see the shape A plot cell graphs an expression in the single variable x, sampled across a range you set. Keep the plotted expression unitless and use x as the horizontal…
- 06 Diagrams that draw themselves A geometry cell renders a labelled figure from your numbers — right(a, b) for a right triangle, triangle(a, b, c) for any triangle. The drawing is driven by…
- 07 Sums, products & the formula library For "add this up over a range," use Sum (capital S): Sum("expression", "index", start, end) — the expression and index go in…
- 08 Matrices & linear algebra Write a matrix with nested brackets, then use the built-in linear-algebra functions — det, inv, transpose, multiplication with *, and more.
- 09 Solve by rearranging — solve() Now the headline feature: NapkinCalc solves equations for you. solve(expression, variable) rearranges expression = 0 to isolate the variable — symbolically, by…
- 10 Goal-seek when you can't rearrange — nsolve() Some equations can't be rearranged cleanly. nsolve("residual", "variable", guess) finds the value that drives the residual to zero…
- 11 Systems of equations — solveSystem() Several equations, several unknowns? solveSystem([equations], "target", [unknowns]) solves them simultaneously. Give it the list of equations, the…
- 12 Show the work — the Steps button NapkinCalc can explain how it reached an answer, not just give it. When a cell does something it can teach — a derivative, an integral, a factorisation, or a…
- 13 Interactive sliders & knobs Any plain numeric definition can become a draggable slider: open its cell menu and choose "Add slider". Drag the knob and every downstream cell —…
- 14 Beyond the basics A few more features worth knowing, each a click away: Images & figures — drop a photo or diagram straight into a cell to annotate your work. Import from…