Puzzles and Riddles

Learning Goals:

  • Determine the missing numbers in equations
  • Develop and apply reasoning skills to make and test math predictions
  • Communicate mathematical thinking orally and visually

The Challenge:

Can you find the mystery number from this square using the clues below?

  1. The number is odd.
  2. It is a multiple of three.
  3. It is smaller than 7×4.
  4. Its tens digit is even.
  5. It is the greater of the two possibilities.

Questions and Prompts to Support your Child:

  • Which clue did you start with? Why did you use that one first?
  • Which clue narrowed things down the most? Which was the least specific?

Extensions & Adaptations:

  • Create a set of clues that will lead someone to a different number from the square. How can you be sure that your clues will lead them to only one possible solution?

Source: NRICH Math