Domino

Reasoning

The excluded domino is number 0 and 0

Reasoning

After identifying all 27 dominoes in the image and comparing to the standard double-six set, the [3|5] domino is absent.

Reasoning

The double-four (4-4) domino is not present among the 27 pictured tiles; every other domino pair from 0 to 6 appears in the image.

Reasoning

The standard double-six set contains 28 unique tiles. Counting the tiles present in the image, we find that all tiles except (1,1) are included. The tile (1,1) is the only one missing because it is the only tile with two 1 dots, and no such tile appears in the image.

Reasoning

A standard double-six domino set has 28 unique tiles. The image shows 27 tiles. Analyzing the image for all number pairs (0-6), the following tiles are present: Doubles: [0, 0], [1, 1], [2, 2], [3, 3], [4, 4], [5, 5], [6, 6] (7 tiles) Pairs with 0: [0, 1], [0, 2], [0, 3], [0, 4], [0, 5], [0, 6] (6 tiles) Pairs with 1: [1, 2], [1, 3], [1, 4], [1, 5], [1, 6] (5 tiles) Pairs with 2: [2, 3], [2, 4], [2, 5], [2, 6] (4 tiles) Pairs with 3: [3, 5], [3, 6] (We are missing [3, 4]) (2 tiles) Pairs with 4: [4, 5], [4, 6] (2 tiles) Pairs with 5: [5, 6] (1 tile) Total tiles present: 7 + 6 + 5 + 4 + 2 + 2 + 1 = 27. The missing tile is [3, 4].

Reasoning

By systematically checking all 28 possible dominoes in a standard double-six set (all unique pairs from 0-0 to 6-6), I identified 27 dominoes present in the image. The only domino missing from the complete set is [4, 4], the double four.