Practice
Generated questions on gates, truth tables and boolean expressions, marked as you go. They never run out, and nothing is stored.
Teaching a class? The worksheet generator puts the same questions on paper, with an answer key, from a link everyone can open — carrying over whichever topic is picked below.
Settings
Which gate has this truth table?
| a | b | Q |
|---|---|---|
| 0 | 0 | 1 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 0 |
Press 1–4 to answer, Enter for the next question.
What comes up
Seven kinds of question, mixed at random.
| Question | What it tests | Stuck? Read |
|---|---|---|
| Gate output | Knowing each gate's behaviour cold | The seven logic gates |
| Identify the gate | Reading a truth table backwards | Truth table generator |
| Evaluate an expression | Operator precedence and substitution | Boolean algebra laws |
| Find the equivalent | Simplification and De Morgan | Boolean algebra calculator |
| Count the ones | Building a truth table in your head | Karnaugh map solver |
| Read a circuit | Getting from a gate diagram to an expression | Logic circuit generator |
| Trace a circuit | Following signals through a diagram to its output | Logic circuit generator |
Then build something
Answering questions about gates is a different skill from wiring them up. When a question stops being obvious, build the circuit and watch it.
Questions
Where do the questions come from?
They are built fresh rather than drawn from a fixed list, so you can keep going indefinitely. The wrong answers are real alternatives rather than filler, so you cannot get there by eliminating the obviously silly ones.
What is covered?
Gate outputs, identifying a gate from its truth table, evaluating an expression at given inputs, spotting an equivalent expression, counting the rows where a function is true, and two kinds of question on a gate diagram: reading its expression off it, and tracing signals to its output. That is most of what an introductory digital logic exercise sheet asks.
Is there a time limit or a score to beat?
No timer. The counter tracks how many you have answered, how many were right and your current streak, and nothing is sent anywhere or stored between visits.
Does it get harder?
For the expression-based questions, yes: three correct answers in a row and it starts drawing longer, more deeply nested expressions; miss one and it drops straight back to the baseline. The level shown next to your streak is where that stands. Diagrams stay the same size at every level, so a circuit is never too big to draw.
Can I answer without a mouse?
Number keys pick an option and Enter moves on once a question is marked, so a whole run can be done from the keyboard.
Can I use IEC symbols or a different notation?
Open "Settings" above the topics to check any mix of ANSI/IEC gate symbols and mathematical/engineering/programming notation. Check more than one and questions draw from all of them at random; it defaults to whichever single one the rest of the site starts on.
Can I go back over what I got wrong?
"Review your misses" appears under the question once you have missed at least one, with the correct answer and a link to go explore it further. It is cleared by reset, like everything else here.
Can I type the answer instead of picking one?
Yes: turn on "Type it instead of choosing" under Settings. For a question that asks for a specific expression, anything with the same truth table is accepted, in any notation, not only the one form shown as an option in multiple choice — typed mode is checked by the same engine that grades the tools, not by matching text.