Why Double-Six Has 28 Fichas

Start with the seven possible values on one half: 0 through 6. Blank can pair with all seven values, including blank. One then adds six new pairs, because blank-one already exists. Continue with five new pairs for two, then four, three, two, and one.

The sum is 7 + 6 + 5 + 4 + 3 + 2 + 1 = 28. Pagat expresses the same idea with the general pairing formula x(x + 1) / 2, where x is the number of possible end values.

Each value appears on seven Fichas. The six suit, for example, runs from blank-six through six-six. The seven doubles are blank-blank, one-one, and so on through six-six.

The International Domino Federation rulebook states that all 28 Fichas contain 168 pips in total. That number can also be checked directly: each value appears seven times, so 7 × (0 + 1 + 2 + 3 + 4 + 5 + 6) = 168.

In the international four-player pairs format, each player selects seven Fichas after the shuffle. Four hands of seven account for all 28, so nothing remains face down to draw.

That complete deal is strategically important: every Ficha is either in a player's hand or eventually visible on the table. Passes and played suits therefore give information that a draw game does not provide in the same way.