Domino

A full double-six domino set contains 28 tiles. By cataloging the tiles in the image, we find: [0,0], [0,1], [0,2], [0,3], [0,4], [0,5], [0,6], [1,1], [1,2], [1,3], [1,4], [1,5], [1,6], [2,2], [2,3], [2,4], [2,5], [2,6], [3,3], [3,4], [3,5], [3,6], [4,4], [4,5], [4,6], [5,5], [5,6]. The only tile from the standard set missing is the double-six [6,6].

After systematically identifying all 27 dominoes visible in the image, I determined that the double-four (4-4) domino is missing from the standard 28-piece double-six domino set. All other combinations from 0-0 through 6-6, including all mixed pairs, are present in the image.

The excluded domino is number 0 and 0

All other domino combinations from 0–6 are present in the image; the only tile not shown is the double six (6,6).

After identifying all 27 dominoes in the image, the complete standard set of 28 double-six dominoes is missing the [0,4] tile. The image contains [0,0], [0,1], [0,2], [0,3], and [0,5], but no domino with a blank side and a 4-dot side (four corners). All other dominoes in the standard set are accounted for, including higher-value tiles like [2,5] and [3,6].