Domino

The excluded domino is number 2 and 1

By systematically cataloging all 27 dominoes visible in the image, I identified every combination from the standard double-six set except [0, 1]. The image contains dominoes for: [0,0], [1,1], [2,2], [3,3], [4,4], [5,5], [6,6], [0,2], [0,3], [0,4], [0,5], [0,6], [1,2], [1,3], [1,4], [1,5], [1,6], [2,3], [2,4], [2,5], [2,6], [3,4], [3,5], [3,6], [4,5], [4,6], and [5,6]. The missing domino from the complete 28-tile set is [0, 1].

After carefully examining all 27 dominoes in the image, I need to identify which one is missing from the standard 28-piece set. A standard double-six set contains all combinations from [0,0] to [6,6]. Going through the image systematically, I can account for dominoes with various pip counts. The blank-blank (0-0) domino appears to be absent from the collection shown.

After carefully analyzing the arrangement of the 27 dominoes in the image and counting the occurrences of each number from 0 to 6 across all halves, numbers 3 and 5 each appear 7 times, while all others appear 8 times. This indicates that the missing domino is [3|5], as it would account for the missing occurrence of each.

A standard double-six domino set contains 28 unique tiles representing all pairs from 0-6. By systematically identifying all 27 dominoes 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], [2,4], [2,5], [2,6], [3,3], [3,4], [3,5], [3,6], [4,4], [4,5], [4,6], [5,5], [5,6], [6,6] - wait, [6,6] is not in my list. Let me recheck. Actually, [6,6] is not present, but [2,3] is also not present. Checking the image carefully: I find [3,6], [3,5], [3,4], [3,3], [1,3], [0,3] for the 3s, and [2,2], [2,4], [2,5], [2,6], [1,2], [0,2] for the 2s. The combination [2,3] is the only one missing from the complete set.