|Here is a puzzle
that may surprise you. Follow these steps:
Pick a number (1-10) __________
Add 11 __________
Multiply by 6 __________
Subtract 3 __________
Divide by 3 __________
Add 5 __________
Divide by 2 __________
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 “calculator."
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
jinx you?) Use the Excel version of the Jinx Calculator to help
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
Share a few
of your interesting examples of numbers that you
Go to the results
page and describe the results.
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