Odd One Out: Find the Number That Doesn't Fit
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In this task you see a group of numbers. All but one share a common property — and that one number is what you are looking for. It trains you to sort numbers quickly by their properties.
Practice odd one out now › Mensa simulationHow it works
- Easy: even and odd numbers.
- Medium: prime versus composite numbers, and divisibility, for example by 3, 4 or 7.
- Hard: several properties at once, square numbers and numbers from the Fibonacci sequence.
Sample question
Which number does not belong?
- 82
- 42
- 52
- 29
- 84
Show solution
29 — The others are even, 29 is odd
Solve this question in the app ›
Tips
- Run through a quick checklist: even? prime? divisible by 3, 5 or 9? a square number?
- The digit sum quickly tells you whether a number is divisible by 3 or 9.
Relevance for IQ and Mensa tests
Odd-one-out questions appear in many intelligence tests, with numbers, words or figures.
Frequently asked questions
Are there odd-one-out questions with words too?
Yes — "What Doesn't Belong? Word Groups" uses the same idea with groups of words.
Does practicing cost anything?
No, all questions are free and can be used without signing up.
Start training ›More question types
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- What Doesn't Belong? Word Groups
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- Figure Matrices Practice
- Logic Grid Practice
- Equation Grid Practice
- Number Figures Practice
- Symbol Equations Practice
- Spatial Reasoning Practice
- Cube Nets and Cube Folding Practice
- Mirror Images Practice
- Memory Test: Train Your Recall