The third player wants to achieve a sum divisible by the divisor 11. The next higher number is 55, the next less 44. To achieve 55, a domino with difference 7 is needed with either 12 or 18 at one end (that means 12-19 oder 18-25, but these combinations are not existing in a game of double-18).
The next possibility is the domino 18-7, which put to the left side opens a fourth end increasing the sum by 7. But this domino is a difference 11, and the dominoes with the difference of the divisor are holy, since they make it possible to improve a scoring move of the previous player. In real life, it will never be put now, except the case its the only domino to move with.
The last possibility means to reduce the sum by four what requires a domino with difference 4. The 12-16 is such one, but put to the end of 12, it increases the sum by 4! Thats not desired and the 18-14 or 12-8 are a better choice. The third player has got one of them, and now we count 18 + 18 + 8 = 44 points. Player no. 3 scores with 44÷11=4 points!
Everybody keeps trying to achive an amount divisible by the divisor. If the player at turn fails, he has to move any other domino. If that isnt possible either, he has to take one from the stack and sits out, and its the next players turn.