27 sheets

Anything will do.

Let the audience recite one.

Then shuffle the cards

Divide into three layers

Show him each stack of cards in turn.

Ask him if he has your card.

Pile his cards in the middle.

Don't shuffle the cards

Continue licensing

Or a three-layer stack

Repeat the above process.

Then put his cards in the middle.

Redistribute cards

This time, his cards must be in the middle of the pile!

I wish the landlord a happy magic!