Binary adder

A binary adder is a digital circuit that performs an arithmetic sum on two binary numbers of any length. 

It is constructed using full adder circuits in series. It has an output carry from one full adder connected to the input carry of the next higher-order full adder. 

It can be represented using the following block diagram:

Working

1. The carry inputs from C0 to C3 are connected in a chain through full adders, and the C4 is the resultant output. 
2. The output from each full-adder is connected to the input of the next full adder of higher order.
3. The sum of outputs generates the required arithmetic sum of bits.
4. The arithmetic sum of the data inputs can be transferred to a third register or to one of the source registers. 

Reference

Binary adder