Domino

The excluded domino is number 2 and 2

By systematically cataloging all 27 visible dominoes in the image and comparing against the 28 tiles in a standard double-six set (which contains all unique pairs where each number ranges from 0-6), the domino [2, 4] is the only tile that is not present in the image. All other 27 dominoes are accounted for.

By counting all 28 tiles in a standard double-six set, I found that the 6-0 (blank-six) tile is the only one missing from the 27 tiles present in the image.

I systematically identified all 28 dominoes in a standard double-six set and compared them to the dominoes visible in the image. After cataloging all visible dominoes, I found that the [0,3] domino (blank-three) is missing from the image.

After identifying all 27 dominoes in the image and comparing to the standard double-six set of 28, the missing tile is the [3|5] domino.

After identifying and listing the 27 visible tiles and comparing them to the complete double-six set (00–66), the only tile not present is the double-six (6,6).

By counting the occurrences of each pip value across all visible dominoes, I found that each number 0-5 appears 7 or 8 times (as expected with one domino missing from the full set), but the number 6 appears only twice. This indicates that a domino containing two 6’s is missing. Additionally, I identified double tiles for 0, 1, 2, 4, and 5 in the set, but no double-6 tile is present. The double-6 [6,6] is the only domino from the standard double-six set that is not visible in the image.