Domino

By systematically cataloging all 27 visible dominoes in the image and comparing against the complete standard double-six domino set (which contains all combinations of numbers 0-6), the domino [2, 4] is the only one missing from the set.

By systematically checking the 28 unique tiles of a standard double-six set against the 27 tiles present in the image, I found that the [6, 6] (double-six) tile is missing.

The image contains 27 dominoes. A standard double-six domino set has 28 tiles. Upon examining the image, we can count the dominoes and check which one is missing. By analyzing the given dominoes, we can see that the domino [6, 6] is not present.

I systematically cataloged all visible dominoes in the image. A standard double-six set has 28 tiles. After identifying all 27 visible dominoes, the missing combination is [0,3] (blank-3), which does not appear anywhere in the image.

I inspected the 27 tiles and every tile from the double-six set is present except the double-six (the tile with six pips on both ends) which does not appear among the shown tiles.

After systematically examining all dominoes in the image, I identified all present dominoes by their dot patterns. The doubles present are [0,0], [1,1], [3,3], and [4,4]. However, the double-two [2,2] (showing 2 dots on both halves) does not appear anywhere in the grid. I verified by checking each row: Row 1 has [1,5], [1,2], [4,6], [4,4]; Row 2 has [4,4], [1,3], [3,4], [1,4], [1,1], [0,2]; Row 3 has [0,1], [1,3], [3,3], [1,4]; Row 4 has [3,4], [2,3], [4,4], [0,2]; Row 5 has [0,3], [0,4], [0,2], [0,0], [1,2]; Row 6 has [3,6], [2,3], [3,5], [0,5]. While [2,3], [0,2], and [1,2] appear, the double [2,2] is conspicuously absent from the complete set.