Question

Total number of inputs in a half adder is __________

(a) 2

(b) 3

(c) 4

(d) 1

The question was asked at a job interview.

My question comes from Half Adder & Full Adder in division Arithmetic Circuits of Digital Circuits

Answer 1

The correct answer is (a) 2

Easiest explanation: Total number of inputs in a half adder is two. Since an EXOR gates has 2 inputs and carry is connected with the input of EXOR gates. The output of half-adder is also 2, them being, SUM and CARRY. The output of EXOR gives SUM and that of AND gives carry.