Domino

By systematically checking against the full double-six set, all tiles are present except for the one with 6 and 2 dots.

After systematically identifying all 27 dominoes visible in the image, I accounted for combinations including [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], [4,5], [4,6], [5,5], [5,6], and [6,6]. The missing domino from the standard 28-tile double-six set is [4,4], which has four pips on both sides.

After carefully cataloging all 27 dominoes visible in the image and comparing them to the complete set of 28 unique domino tiles (0-0 through 6-6), I identified that the domino with values 1 and 3 is missing from the arrangement.

The excluded domino is number 0 and 0

Counting occurrences of each end value (0–6) among the 27 shown dominoes reveals that the values 2 and 5 each appear only six times while every other value appears seven times. Therefore the missing domino is the one containing 2 and 5.

After counting the occurrences of each number across all halves in the 27 dominoes, numbers 0,1,2,4,6 appear 8 times each, while 3 and 5 appear 7 times each, indicating the [3-5] domino is missing.

After analyzing the 27 dominoes present in the set, I identified all numbers 1-6 appearing in various combinations, but the double-zero tile [0,0] is not visible in the layout. The double-blank domino would appear as two empty halves, and in the ASCII art representation, this corresponds to the missing gap that should complete the standard 28-tile double-six set.