double dominoDouble-six dominoes, with 28 tiles; Double-nine dominoes, with 55 tiles; Double-fifteen dominoes with 136 tiles; Double-ehteen dominoes with 190 tiles; Getting Started Equipment and numberA double-12 domino. A double is any tile with identical pips on both sides. Using a quarter or penny is a great way to mark an open train or station. Each player’s first move & opening private trains