The machine uses an encoder code inputs into binary, and send it to the multiplier / adder / subtractor. The pulse goes to the system you required, and adds / subtracts / multiplies the input. The output is then put through a decoder to tun it into a number and then the appropriate light on the board is lit. While it processes it may light up random numbers before finalizing on 1. The machine can use 0 correctly and you can multiply / add / subtract by 0. The subtracter and adder are RCA's. On the subtractor the input will go in, and will come out with a number that is either positive or negative. If it is positive it will go to a different decoder than if it was negative. The multiplier is based off of a torch tower that multiplies the input, and then the inputs are put through an overflow mechanic (Thats the spaghetti) and then put through a decoder. The decoder sends the correct signal to the board.
Hit a button for the operation you would like. The equation will always be Top +/-/* Bottom. After putting in input in about 3 to 15 seconds the correct answer will be on the board.