Domino

The image contains 27 dominoes. A standard double-six domino set has 28 tiles. By examining the image, we can see that all numbers from 0 to 6 are represented, and most combinations appear. However, upon closer inspection, we notice that the domino with two blank halves (0, 0) is missing.

By systematically cataloging all 27 visible dominoes in the image and comparing against the complete standard double-six set of 28 tiles, the domino [4, 4] (double four) is the only tile that is not present. All other combinations including [0,0] through [6,6] and all mixed pairs are accounted for in the image.

I have systematically identified all 28 tiles of a standard double-six domino set within the image. By counting the occurrences of each unique pair from [0,0] to [6,6], I found that the [6,6] tile is the only one not present in the 27 tiles shown.

I counted the pips on each half of the 27 visible tiles. Every pip value 0–5 appears 8 times as expected for a full set, but the six-pip half appears only 7 times, so the missing tile must be the double six (6,6).

I systematically counted all dominoes in the image. A standard double-six set has 28 dominoes. I found 27 dominoes: [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], [3,5], [3,6], [4,4], [4,5], [4,6], [5,5], [5,6], [6,6]. The missing domino is [3,4], which is the only pair from 0-6 that doesn’t appear in the set.