Write down on a piece of paper sequentially numbers 1, 2, 3, 4, 5, 6, 7, 8, 9. Ask someone from the audience to fold in the mind of any three numbers that follow one another. And the result is called. For example, he will choose 4, 5 and 6. In this case, the sum is 15. Then immediately call the planned figures.
To do this trick, you do not need to be a great mathematician or a great magician. Just need a little ingenuity.
When the call amount, in the mind divide it by 3. In this case you would have 5. It is not that other, as the average figure. Can only be called a figure standing in front of her - 4, then the following two 5 and 6.
The whole effect of this focus in a lightning response. For those who are able to quickly count the number of digits can be increased to twenty or more.