The number indicated on the card corresponds to the number of copies in the deck, i.e. one 1 card, two 2 cards and ten 10 cards. Thanks to this strong principle, it is possible to evaluate the cards remaining in the draw pile, and therefore to take risks and make the right decision.
In Jour de Chance, you have to get as close as possible to 21 points either by provoking a pair of cards, or by scoring one of your cards or that of an opponent. But, if you go over 21 points, you lose and the game ends. So you have to be careful but also know how to take risks at the right time.
When the game ends, the winner closest to 21 points wins the game.