Most calculators make you commit before you can think. Tap a number, tap an operator, the previous value is gone. Real math is messier: a rough trip budget, a freelance invoice, a recipe scaled up. You want to see the whole thing, edit a line, and watch the rest update. My workaround was a notes app. Write "flight 420, hotel 3 nights at 180 each", do the arithmetic in my head. Context preserved, but not actually calculation. Sigma is the scratchpad I wanted. Type math in plain language, results appear live on the right. "20% tip on 84.50", "rent + utilities", "120 EUR in USD". Variables, currencies, unit conversions, dates, all inline. Everything stays editable. A few things I left out of the description: built-in themes, a calculation reference you can pull up while typing, and full French localisation. iPhone-only on purpose for v1, the design and parser are tuned for one-handed thumb typing. Free to start with three sheets. Pro is $1.99/mo, $14.99/yr with a 7-day free trial, or $29.99 lifetime, and unlocks unlimited sheets, iCloud sync, and export to PDF, Markdown, or plain text. I'm the solo dev. Ask me anything: parser choices, why iPhone-only or what's next on the roadmap.

Sigma Notepad Calculator

The notepad calculator iPhone never had.

The notepad calculator iPhone never had.