Question

How many AND, OR and EXOR gates are required for the configuration of full adder?

(a) 1, 2, 2

(b) 2, 1, 2

(c) 3, 1, 2

(d) 4, 0, 1

The question was asked during an internship interview.

The origin of the question is Half Adder & Full Adder in section Arithmetic Circuits of Digital Circuits

Answer 1

Correct answer is (b) 2, 1, 2

Explanation: There are 2 AND, 1 OR and 2 EXOR gates required for the configuration of full adder, provided using half adder. Otherwise, configuration of full adder would require 3 AND, 2 OR and 2 EXOR.