Process

// b.Underline the words that are time markers. //
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...

// c. Play and try to explain why the magic trick worked. //
I really don't have any idea of how it works maybe it really is a magic trick, although it is impossible.

No it wasn't what I was thinking. The truth is, that I __will__ WOULD never figure out that the trick was in a simple ecuation that always results on multiples of 9 and of course, I didn't notice that every time I click on "check it" the shapes on the cells were changing.