Parrot fortune-telling algorithm
The first one contains: 1, 3, 5, 7, 9, ...
The second contains: 2, 3, 6, 7, 10. ...
The third contains: 4, 5, 6, 7, 12. ...
The fourth picture includes: 8, 9, 10, 1 1, 12, ...
……
In the future, just add up the first numbers of the cards that you said have the number you want, and it will be the number you want.
It is estimated that the gentleman used a similar method. This is the first step. The second part is training parrots. Usually a millet sticks to a card, and the parrot will naturally take it out (in fact, it is to eat millet). After the conditioned reflex is formed, when taking out a stack of cards, just turn the required card over (or turn it around) so that it can see a point on the card in front of the parrot (maybe you can't see it because of the angle), and it will peck it out. Then feed him another grain of rice.