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medium importance~0-1 Q in Tier 16 formulas⚡ 7 shortcuts3 subtopics

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Dice: finding opposite faces from positions

Standard die
1+6 = 2+5 = 3+4 = 7

Opposite faces of a standard die add to 7.

Hidden faces of a standard die
\text{hidden} = 21 - \text{shown}

All six faces add to 21.

Painted cube cut into small cubes

Two faces painted
12(n-2)

Cubes on the edges, not the corners.

One face painted
6(n-2)^2

Cubes in the middle of each face.

No face painted
(n-2)^3

The hidden inner block.

Total check
8 + 12(n-2) + 6(n-2)^2 + (n-2)^3 = n^3

The four counts add up to all the small cubes.