Puzzles

One activity that many of our members enjoy is puzzling! You can test yourself for fun with our brainteasers. Our quizzes and conundrums are updated regularly, so do check back on the page for the latest content, and if you get really good at them, why not find out what your IQ is by booking a Mensa Supervised IQ Test?

16/12/2025 – Mince Pie Chart

Place the numbers 0-9 in the diagram below such that:

  1. The two highlighted sectors sum to twelve
  2. No adjacent sectors sum to 10, 11 or 12
  3. No adjacent sectors contain consecutive numbers
  4. Prime numbers are not adjacent to each other
  5. Positive square numbers are not adjacent

Pie chart

Puzzle courtesy of Mensa member Peter Hooton

  • Show Answer

 

As the shaded squares sum to 12, then the possibilities are (3, 9), (4, 8) or (5, 7).

Of these, 3, 5 and 7 are prime, so they can’t be placed next to the 2 given. Equally, 8 + 2 or 9 + 2 breaks the second condition, so the number next to 2 must be 4, and the other shaded sector must be 8.

The sector on the other side of 4 cannot be 1 or 9 (as these are square), 3 or 5 (consecutive numbers) or 6, 7 (sum to 10, 11, 12). Therefore, it must be 0.

Between 2 and 8, we now have a choice of 1, 3, 5, 6, 7 or 9. 1, 3, 7 and 9 are adjacent, leaving a choice of 5 or 6. 5 is prime (as is 2), so the sector must equal 6.

On the other side of the circle, we need to fit in the odd numbers 1, 3, 5, 7, 9. Being prime 3, 5 and 7 need to occupy alternate sectors – one of which must be next to the number 8. This cannot be 3 (sum to 11) or 7 (adjacent), so it must be 5. 9 cannot border 3, so it must be next to 5. 7, 1, 3 fill in easily from there.

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