Mathe-magic

For this 15 minute activity with the class, I used this opportunity that was given to me to show some math magic to this class even though I'm not teaching them mathematics.

This "magic" begins by having a pupil select a month of their choice.
In this case, a student named Germaine(Did i spell it out right?) was picked and she selected the month of October.

She proceeded to choose a 4 x 4 dates on the calender and I wrote them down on the whiteboard.
I began my prediction and input the 'prediction' on the calculator which happens to be the value of 68.

Germaine then chose 4 numbers of her choice. For every number that she chose, the numbers of the same row and column will be striked out and she can't chose those numbers again. The end result looked like this....


Let me remind you again that the numbers Germaine chose were of her own free will. Add up the numbers that she chose and guess what?

The sum of all numbers is 68.

Thinking Activity for students of 5-8.

Is it true that all numbers will result in 68? Can you try it on other months and other numbers see if the result is still 68?

Mr Xie.