What do people do to make a math tricks?

Answer 1

Math tricks can be easily created by using simple mathematical computation and hiding it in a trick. For example, think of a number between 1 and 25. Now add 5. Multiply by 2. Subtract 8. Divide by 2. Add 9. Subtract your original number. Now I'll predict the number you have: 10! This is easily proven using algebra (no matter what number you choose, the result is the same). We will let x represent the number the other person chooses. Now the final result would equal: (((2(x + 5) - 8) / 2) + 9) - x = 10 This may look confusing with all the parenthesis, but it is actually quite simple. When we simplify we get: (2x + 2)/2 + 9 - x = 10. And then: x + 1 + 9 - x = 10. Finally: 10 = 10. Note that it doesn't matter what the value of x is (the original number the other person chooses). This is why we can "predict" what their resulting number is.