Full adder definition check: A full adder adds two data bits and, by definition, includes both a carry input and a carry output. Evaluate the claim that it “need not” have carry in/out.

Introduction / Context:
This item distinguishes a full adder from a half adder. A full adder is the standard 1-bit building block used to construct multi-bit adders because it accepts a carry in (Cin) and produces a carry out (Cout).

Given Data / Assumptions:

• Terminology: half adder vs full adder.
• Target: definition, not a specific IC.

Concept / Approach:
A half adder adds two bits (A, B) but has no Cin. A full adder adds A, B, and Cin, producing Sum and Cout. Multi-bit adders cascade full adders by wiring each stage’s Cout to the next stage’s Cin, enabling n-bit arithmetic.

Step-by-Step Solution:

Verification / Alternative check:
Common logic equations: Sum = A xor B xor Cin; Cout = majority(A, B, Cin). These require Cin and produce Cout.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing half adders with full adders.

Final Answer:
Incorrect