Lesson:
Jinx Puzzle 


Here is a puzzle
that may surprise you. Follow these steps: Pick a number (110) __________ Add 11 __________ Multiply by 6 __________ Subtract 3 __________ Divide by 3 __________ Add 5 __________ Divide by 2 __________ Subtract the original number __________ Your answer is: __________ Does this puzzle always work? (That is, are you always jinxed with the number 13?) Try it again with 3 different numbers. (They don't have to be between 1 and 10.)
Do you think you will
always get 13 no matter what number you try?
Could you find a number that will unjinx the jinx puzzle? The Jinx Calculator
To help you find out if this puzzle will work for all numbers, we will use a special spreadsheet â€ścalculator." Here's what your Jinx Calculator will look when you open it. Notice that 6 was the chosen number and entered in cell B1. The spreadsheet then quickly did
all the calculations and the answer was once again
13  the unlucky number. Can you find a number that
will make the puzzle not end in 13 (and
not
jinx you?) Use the Excel version of the Jinx Calculator to help
you. (Hint: Try
different kinds of numbers not just whole
numbers. Like these: 2.5, 56, 3000,
999999999, .000005. Fractions can also be tried.
For example if you try 1/2, you enter =1/2 into
the cell. Share a few
of your interesting examples of numbers that you
used here. Go to the results
page and describe the results. Questions:
Is it possible to try all numbers on the spreadsheet? If not, what are some numbers we can't use in a spreadsheet? Source: Original Version
1.0 developed at CIESE
Center for Innovation in Engineering & Science Education (2007) Revised 11.13.19 currently under construction 