Truth table size for multi-input logic For a combinational circuit with four binary inputs, determine how many rows (entries) are required in the complete truth table. Justify using the 2^n rule.

Introduction / Context:
Truth tables enumerate all possible input combinations and corresponding outputs for logic circuits. Knowing the number of required rows helps in designing, verifying, and minimizing logic using methods like Karnaugh maps or Boolean algebra.

Given Data / Assumptions:

• Number of binary inputs n = 4.
• Each input can be 0 or 1.
• All combinations must be considered.

Concept / Approach:
For n independent binary inputs, the number of unique input combinations is 2^n. Each combination corresponds to one row in the truth table. Therefore, for four inputs, total rows = 2^4 = 16.

Step-by-Step Solution:

Verification / Alternative check:
List bits as A B C D. Counting in binary from 0000 to 1111 yields exactly 16 patterns, confirming the result without omission or duplication.

Why Other Options Are Wrong:

• 4 or 8 or 12: These do not equal 2^4 and would miss valid input combinations, leading to incomplete analysis.

Common Pitfalls:
Forgetting that each additional binary input doubles the table size; mixing up the number of outputs with table size (outputs do not change the number of rows, only the number of columns in the table).

Final Answer:
16