I built GridCalc, an RPN spreadsheet for iOS.

It combines the efficiency of Reverse Polish Notation with the visible structure and reactivity of a spreadsheet. You enter numbers and operators step by step, and you can retroactively change any value. All dependent calculations update immediately.

I love spreadsheets but I've never liked how cramped traditional spreadsheets feel on a phone. My goal was to make ad‑hoc, spreadsheet-like calculation on a phone feel direct and fluid.

Here’s a short demo: https://youtu.be/M0HwzrGGuyc

App Store link: https://apps.apple.com/us/app/gridcalc/id6759011187

Happy to answer questions.