Question

Which of the following is correct for full adders?

(a) Full adders have the capability of directly adding decimal numbers

(b) Full adders are used to make half adders

(c) Full adders are limited to two inputs since there are only two binary digits

(d) In a parallel full adder, the first stage may be a half adder

This question was posed to me during an internship interview.

My question comes from 4-Bit Parallel Adder/Subtractor topic in chapter Arithmetic Circuits of Digital Circuits

Answer 1

Correct answer is (d) In a parallel full adder, the first stage may be a half adder

To explain: By using maximum of two half adders we can make a full adder for the first stage of a Parallel Full adder.