Pocket Sized Arduino Calculator Makes A Great First Project. 13 Comments . by: Tom Nardi ... [Danko] is using an array of 17 tactile switches for the keyboard and a very crisp 128×32 I2C OLED ...

This calculator solves a more practical problem — the dearth of RPN calculators on the market with the correct keyboard feel, specifically with the large keys and light touch he desired.

Featuring an Arduino Nano microcontroller board and the keyboard from a small numeric keypad the LCD display the calculator is powered by a set of AA batteries through a DC-to-DC converter.