Process

**II. Assignment**
 * LATE 2pts**

Check the following web page in which you have a magic trick. []

Follow these steps: 1. Read the instructions, cut them and paste them ** to your wiki **. 2.Underline the words that are time markers. 3. Play and try to explain why the magic trick worked. 4. Check the explanation below the trick. Was it the one you were thinking of? Explain.

=An Arithmetic Magic Trick = __Think__ of a 2-digit integer. __Subtract__ from the number the sum of its digits and __find__ the result in the table below. __Note__ that each cell of the table contains a number and a geometric shape. __Concentrate__ hard on the shape that shares a cell with the result of your calculations. __When ready__, __press__ the "Check it!" button ...

3-The magic trick works because all possible solutions of subtract to a two-digits integers the sum of its digits, in the table, have the same shape. 4-Yes, necessarily all solutions should have the same figure, only had to calculate the equation that modeled the problem above. As a two-digits integer can be written in the form 10a+b with a,b integers between 0 and 9, was clear, doing the subtract 10a+b-(a+b), that the number thought will always be multiple of 9 and with this we get the rule for the trick