Rutgers/Lucent ALLIES IN TEACHING MATHEMATICS AND TECHNOLOGY Grant
Using technology not simply to do things better, but to do better things.

Thinking About Teaching Mathematics:
A 2-Digit Number Puzzler


  • Select and record a 2-digit number; this will be referred to as the "original".

  • Find the digit sum.

  • Find the difference: (Original - Digit Sum).
    Example:
          Original = 73
       Digit Sum = 10
      Difference = 73 - 10 = 63


  • Do this with a variety of starting numbers. Can you find a pattern in the differences?

  • How can you explain this pattern?


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