You will have people saying “how in the world did you do that?”
Let’s say you are sitting with some friends. Or better yet, children or grandchildren. You volunteer to predict a four digit number. And you write it down on a card and turn it over.
You ask someone to write down three single-digit numbers without repeating a number. Then have them reverse the numbers and subtract the smaller from the larger.
You take that number, reverse it and add the two numbers together. The total will be “1089” — the number you wrote down on the card.
The good news is that – whatever the first three numbers are, the end result is always “1089.” And no – I don’t know how it works. Unless I take off my socks and shoes. And even then. . . . . .