The B4 Computer Processor Kit and the B4 Primary School Starter Kit come with a 4-bit adder module. This allows us to add numbers as long as the sum is not larger than 15. But what if we want to add larger numbers, such as one billion, or a trillion? For this, we can daisy-chain multiple adder modules and connect the carry-out bit of one adder with the carry-in of the next adder. With this in mind, we have tried an experiment in class and connected 16 adders! And since 16x4=6