Effect:

Three coins increase to six in your hand.

Procedure:

Show the spectators three coins and count them out onto the magazine you prepared. Your spectators don't know that there are more coins hidden inside the magazine cover.

Fold the magazine slightly and tip the three visible coins into your hand. The three hidden coins will slip out of the magazine and into your hands at the same time.

Slowly open your hand to that the coins have mysteriously doubled to six.