Domino

By systematically checking each tile in a standard double-six set, all combinations except for [0, 6] are present in the image. The set contains 27 tiles, and the missing one is the blank-six domino.

The image contains 27 domino tiles. Upon examining the image, we can see that all possible combinations of numbers from 0 to 6 are represented except for the double-zero domino.

By systematically checking all 28 possible dominoes in a standard double-six set, I counted the occurrences of each combination. All dominoes from [0,0] through [6,6] are present in the image except for [4,4], which would show four dots on the left side and four dots on the right side arranged in a square pattern. This is the only domino missing from the complete set of 28 tiles.

After identifying and tallying all shown tiles from the image against the full double-six set, the only pair not present is the domino with 2 and 4.

A standard double-six domino set contains 28 tiles. By analyzing the 27 dominoes shown in the image, I identified all tiles by counting dots on each half. The dominoes containing a 6 are: [0,6] (Row 3, first domino), [1,6] (Row 4, second domino - identified by the 6-dot pattern on the right side), [3,6] (Row 1, fourth domino), [4,6] (Row 2, second domino), [5,6] (Row 6, sixth domino), and [6,6] (Row 3, sixth domino). Since there should be 7 dominoes with a 6 (one for each pairing 0-6), and only 6 are present, the missing domino must be the remaining one from this series: [2,6]. All other dominoes in the standard set are accounted for in the image.