Ages 12–16
BrainteenAges 13–18PuzzlesPuzzle
Odd one out (Expert)
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Find the number that does not belong with the other three.
Curriculum links
- Common Core 4.OA.B.4: Find factor pairs for whole numbers up to 100, recognise multiples, and decide whether a number is prime or composite.
- England NC Y5.MA.MD.2: Know the vocabulary of prime numbers, prime factors and composite numbers, and say whether a number up to 100 is prime.
- England NC Y5.MA.MD.8: Recognise and use square numbers and cube numbers, and the notation for squared (²) and cubed (³).
- BNCC EF06MA05: Classify numbers as prime or composite, use "multiple of", "divisor of" and "factor of", and find divisibility rules.
- Programmes FR C4.MA.NC.3: Use multiples, divisors and prime numbers; decompose a number into prime factors.
Licence: Crayonbird original
Also in: हिन्दी
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About this activity
What your child practises
Skills: Odd one out: number properties (level 3).
Logical reasoning, patience and step-by-step problem solving.
What’s included
- 15 questions
- An answer key you can print with the sheet or on its own
- An on-screen version with instant marking and stars
Age and school year
Made for ages 13–18. That’s Grade 8–12 in the US, Year 9–13 in England, JSS 2 – SS 3 in Nigeria and Class 8–12 in India.
How to use it
- Print it at home or school – it fits a standard A4 or US Letter page.
- Print the answer key too, so marking takes seconds.
- Play it on screen: answers are marked instantly and children earn stars.
- Write on it on a tablet or touchscreen with a finger or stylus – no printer needed.
Tips for parents and teachers
- Hold back the answer and give a small hint instead (“Look at the top row”), so the “aha!” moment stays theirs.
- Puzzles make great early-finisher or calm-down activities – keep a few printed copies in a folder.
- Combine this sheet with past exam questions on the same topic for mixed, exam-style practice.
Good to know
- Time needed
- About 5–10 minutes
- You’ll need
- A printer (or a tablet to work on screen), a pencil and an eraser
- Difficulty
- Harder (Expert) – pitched at ages 13–18
- Answer key
- Yes – print it with the sheet or on its own