I did this once before, now I feel its time to do it again.
I am thinking of a number between one and ten. I promise you that I have selected one number and it will not change. In one week, I will tell everyone what my number is. In the mean time, you may guess and we will see how many get it right.
There was a mystery/thriller called “Think of a Number” that used a plot point where the bad guy sent a letter to someone telling him to pick a number, then when the recipient opened the inner envelope it had the number he had picked. Magic by postal mail. My review.