- Now, we can combine the half adder and the full adder to construct a 2-bit adder.
- The least significant bit does not require a full adder as there is no carry input.
- The half adder determines the least significant bit of the sum as the XOR of the least significant bits of the inputs.
- The carry output of the half adder becomes the carry input of the full adder.
- The full adder computes the sum of the inputs
*A*_{1}and*A*_{2}and the carry bit. **Example:***A*=3 (11) and*B*=1 (01):*S*_{0}=0*S*_{1}=0- Result: 100, which is the binary representation of 4.