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Mystery Number

Problem Statement


  Investigations | Algebra | Functions & Equation   Additional Investigations | Mystery Number

What is the mystery number? If I subtract 1 / 2 of it, then multiply by 3, and then add 2, the end result is 26.

Problem setup

What is the original number if I half it, subtract that half, multiply the result by three, add two to that result and end up with 26?


Plans to Solve/Investigate the Problem

I decided to use the Guess and Check strategy to solve this problem.


Investigation/Exploration of the Problem

I began guessing with the number 30, but the final result was 47. Then I tried 10 and that result was 17. When I tried to use 20, the result was 32. I guessed at 16 and voila---that was the answer! 16 divided by 2 is 8 times 3 is 24 plus 2 equals 26.


Extensions of the Problem

Extension: Write your own mystery number problem to have a classmate or friend solve. Make sure that your number goes through three transformations (addition, subtraction, multiplication or division).


What is the original number if I multiply it by 2, subtract 50, then add 8 and get 50?

Author & Contact
Pam Joseph
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