Deriving an Expression from a Truth Table — Boolean Logic and Expressions | IGCSE Computer Science

Exam Frequency Analysis

Past paper frequency (2018 to 2024)

This topic accounts for approximately 6% of your exam marks.

stable

Low

Stable6%

Writing Boolean expressions from logic diagrams and simplifying using laws appear regularly.

When the question gives you a truth table and asks for the Boolean expression, the standard method is: write one AND term per row where the output is 1, then OR all those AND terms together.

Method. (1) Find every row where Q = 1. (2) For each such row, write an AND term that is true on that row only: use the variable directly when its value in that row is 1, and ¬variable when its value is 0. (3) OR all the AND terms together.