Prediction

A simple trick, yet it takes time to practice. It was a trick presented by Cyril.
prepare 20 white cards, completely white!

This should be done before the performance. Write no.1- 7. The numbers must be written in front & back of the white cards. Then, write no.8 only in the front part of the white card. Arrange the the cards from no. 8-1, of course, the spectators only saw white surface of the top cards which is no.8 written.
Then, turn all the cards over to the bottom.
The preparation is done.
Tell your spectator you are going to write some number on the white cards you held. But, they're not going to know what the number is, so you just cover all the cards on a table. Secretly, you write no.9 to 9 cards. All must be the same number.
There are 9 cards with no.9 written now. Ask your spectator which card he/she thinks is no.1? Then, a spectator will choose one of the card, so you write no.1 on that blank part of the card. Do the same thing to no. 2,3....until no.8.
When spectator chose the card he thinks is no.8, give him a pen to write no.9 on the last card left on table. While spectator was doing this, flip the whole deck of your cards to the previous cards with written numbers. Take the pen back from spectator and write no.8 on your card. ( Remember the card left one surface blank?) Now, flip over the card on the table, asking will your prediction right? Of course, the card written no.9 will be written no.9 on its back too! Then, do the same thing to the rest of the cards and numbers.