Logic gate calculator with 2-bit input and 3-bit output. 

Simplified version of the original circuit by Vicas Danys.

Usage:

There are 4 binary button inputs and 3 lights. The binary inputs are split (left and right). The first two are one integer, the second two are the second integer. Upon adding them, they will display the output (sum) in the the 3 LEDs as a 3-bit integer.​