The board is essentially an Arduino with a standard USB to serial chip and a MAX7219 display driver. Of course, you could breadboard up all of these things, but it wouldn’t be as neat looking.

But we can’t deny this Arduino calculator project by [Danko Bertović] ... is using an array of 17 tactile switches for the keyboard and a very crisp 128×32 I2C OLED display. Beyond the ...

This is the SB116, an 8-bit programmer’s calculator powered by an Arduino Nano. It features a 128 x 64 pixel monochrome OLED display and can be powered by either a USB port or three AAA batteries.

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.

The finished circuit can display numbers ranging from 0 through 1023, in connection with a 10K preset pot attached to the analog input A0 of the Arduino board. This 4 -digit 7-segment display section ...