Domino

The image contains 27 dominoes. A standard double-six domino set contains 28 unique tiles. Upon examining the image, all possible pairs of numbers from 0 to 6 are present except for the domino with both halves showing 6 dots. Therefore, the missing domino is [6, 6].

By systematically checking all 28 possible domino combinations (each pair of numbers from 0-6, including doubles), I identified 27 dominoes in the image. The domino [2, 5] (or equivalently [5, 2]) is the only combination from the standard double-six set that does not appear in the provided image.

A standard set of 28 double-six dominoes includes pairs ranging from 0-0 to 6-6. After identifying all 27 dominoes present in the image (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 missing is the double-six (6-6).

By systematically going through the standard 28-domino set and checking each domino visible in the image, I can identify which one is missing. After cataloging all visible dominoes, the [0,2] domino (blank-two) is not present in the image.

After listing each domino visible in the image and comparing to the complete double-six set, the only pair not present is the domino with 3 and 5.

After systematically identifying all 27 dominoes present in the image by counting dots on each tile, I verified that every standard double-six domino is accounted for except for the [0,6] combination. The set includes [0,0], [0,1], [0,2], [0,3], [0,4], [0,5] but no domino with 0 on one side and 6 on the other. All other dominoes from the standard 28-tile set are present in the image.