We'll give this a try and see if it works ...
1. On a piece of paper, write down a three or four digit number
Make it completely random with lots of different digits, like 6710 or 741
2. Jumble up all the digits in your number to make another number
So, if you chose 2875, you could make 5287
3. And now that you have two numbers, subtract the smaller number from the larger one.
eg. 5287 minus 2878
4. Ok, now draw a circle around one of the digits in your answer
But don't pick a 0 because that's already a circle!
5. Finally, jumble up all the numbers in your answer and post them, except for the one you circled.
So, if your answer was 7570, you could draw a circle around one of the sevens and post 570 or 705.
I will tell you what your circled number was ...