160083

In this activity, the calculator reverses the sum to get the number that you chose. By doing this it can easily figure out what your number is.

For example, if my number was 10 I would have to add 4, which equals 14, then double it which equals 28 and then subtract 7 which equals 21.

So, when you have to tell the calculator what your final answer was, it will do the complete opposite of what it told you to do. I gave them the number 21 so what the calculator will do is add 7 which equals 28, halve it which equals 14 and then subtract 4 which equals 10. 10 was my original number, so that proves that the calculator reverses the sum.

More answers to prove;

* (11 + 4) x 2 - 7 = 23
Calculator working = 23 + 7 ÷ 2 - 4 = 11