Minecraft wiki entry for Calculator, associated text: The multiplier is probably the most complicated part of the calculator. For our purposes, multiplication is a repeated addition. That means that, once again, adders will be used here. Before you add the adders, you actually have to set up an AND gate (not including the control one). Its use is simple: in binary multiplication, because only 0's and 1's are used, the only way that we can have an output is by multiplying 1 by 1.