Mathematical Fooler is in fact an impossible location effect. It really is a fooler! The principle appears as already known but will succeed in deceiving even the fellow magicians!
First of all it is possible to proceed with a borrowed deck , a real selling point. The magician borrows a deck. He asks the spectator to cut a third of the deck and count how many cards he has in his hand. It will certainly have a two-digit number. The spectator adds the two digits together and looks at the card that corresponds to that position from the bottom of the packet. Finally he loses the packet in the center of the rest of the deck! These are impossible conditions! Despite this the magician is able to:

1- Reveal the number thought by the spectator and how many cards he has cut
2- Reveal the selected card!

All this with a borrowed deck and NO gimmick!
Easy to do !