Domino

In a complete double-six set, every pips value (0 through 6) appears exactly 12 times across all 28 dominoes. By systematically counting the pips on the 27 visi...

After identifying all 27 dominoes present in the image, the domino with 0 pips on one side and 1 pip on the other was found to be missing from the set.

Comparing the 27 visible dominoes against all 28 combinations in a double-six set, every pair is represented except 2-5.

Reading the pip values across the board, the 5-pip halves are sparse and the 5-6 combination does not appear among the visible dominoes, so it is the best guess...

Comparing the dominoes on the board against the double-six set, the 2-5 pair is the one that does not appear.

The board contains 27 dominoes. Systematically checking every unordered pair 0-0 through 6-6, the double-six (6-6) with 12 pips never appears while all other 27...