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Reasoning · Chapter 14 · Non-Verbal

Cubes and Dice

Two related question types share this chapter: finding which face lies opposite another on a die shown from different angles, and counting how many small cubes get painted when a larger cube is cut apart. No question from this topic appeared in the papers I could extract or recover, so this chapter is built entirely to the AAI pattern.

Concept video — watch on the AAI ATC Exam Prep channel
2–3questions per shift
50 sectarget time each
3subtopics
0PYQs — pattern only
Objectives 1. Standard dice 2. Opposite faces from views 3. Painted cube cutting Summary Assessment Free PDF
Before you start

Learning objectives and outcomes

A cube always has three pairs of opposite faces. Every question in this chapter is really about pinning down those three pairs, or about counting how many of many small cubes touch the outer surface in a particular way.

Objective 1Know the standard dice rule and recognise when it does and does not apply.
Objective 2Deduce opposite faces of a non-standard die from two or more given views.
Objective 3Apply the rule that faces seen together in one view can never be opposite each other.
Objective 4Count corner, edge, face and fully hidden cubes after a painted cube is cut into smaller cubes.
Outcome ASolve an opposite-face question from three views without redrawing the whole cube.
Outcome BApply the four cube-cutting formulas directly, for any cube cut into n³ smaller cubes.
Subtopic 1

Standard dice and the sum-to-seven rule

A standard die is numbered 1 to 6 and follows one universal rule: opposite faces always add up to seven. This rule applies only to a die explicitly described as standard, never to a die carrying letters, symbols, or colours.

The sum-to-seven rule

1 is opposite 6  ·  2 is opposite 5  ·  3 is opposite 4

Every pair adds to seven. This is the single fact to know for a standard die, and nothing more needs to be deduced from any picture.

1 · 6
opposite pair1 + 6 = 7
2 · 5
opposite pair2 + 5 = 7
3 · 4
opposite pair3 + 4 = 7
Figure 14.1 — A standard die and its three opposite pairs A single cube shown from a slightly angled view with three visible faces numbered 1, 2 and 3, and dotted lines pointing to the three hidden faces on the far side labelled 6, 5 and 4 respectively, illustrating the three pairs that each sum to seven. Upload image here
✈ AAI ATC relevance — cubes and dice questions appear in most reasoning sections, usually two to three per shift
Memory trick — "Only if it says standard"

The sum-to-seven rule is the most misapplied rule in this whole chapter. If the die shows letters or symbols instead of numbers 1 to 6, or if the question does not say "standard die," this rule does not apply at all, and the opposite faces must be worked out from the views given.

EasyATC Pattern
On a standard die, the face opposite the one showing 2 is:
On a standard die, opposite faces sum to 7, so the face opposite 2 is 5.
ModerateATC Pattern
A die shows the letters P, Q, R, S, T and U on its six faces, with no numbers at all. The sum-to-seven rule:
The sum-to-seven rule is specific to a standard die numbered 1 to 6. A die with letters carries no such built-in rule, and its opposite faces must be deduced from the views actually given in the question.
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Subtopic 2 · highest yield

Finding opposite faces from two or more views

When a die carries letters or symbols, its opposite faces are not fixed by any universal rule. Instead, they must be worked out from however many different views the question shows.

The one rule that always holds

Any two faces seen together in a single view can never be opposite each other — they must be adjacent.

A cube shows at most three faces at once, and those three all meet at one corner, so none of them can be opposite any other. Every pair you see together in one picture rules that pair out as a possible opposite pair.

Shortcut — two views, two faces in common

If two different views of the same die share two common faces, the two faces that are not common between the views must be opposite each other.

This is a direct consequence of the rule above: since the two common faces are already known to be adjacent to everything else shown, the only faces left unexplained are the two that switched — and the only relationship two faces can have on a cube, if not adjacent, is opposite.

Figure 14.2 — Two views sharing two common faces Two drawings of the same die side by side, the first showing faces marked P, Q and R and the second showing faces P, Q and S, with P and Q highlighted as the common faces in both views and R and S circled to show they are the two faces deduced to be opposite each other. Upload image here
Memory trick — "List every adjacent pair you see, then eliminate"

Across all the given views, write down every pair of faces that ever appear together. Those pairs are all adjacent, never opposite. With three views covering all six faces, elimination alone often reveals all three opposite pairs without needing the two-common-faces shortcut at all.

Worked example

A die with faces A, B, C, D, E and F is shown in two positions. Position 1 shows A on top, B in front, and C on the right. Position 2 shows A on top, B in front, and D on the right. What can be deduced?

  1. The two views share two common faces: A and B appear in both.
  2. The face that changed is the one on the right: C in the first view, D in the second.
  3. By the shortcut rule, since A and B are common and everything else is fixed relative to them, C and D must be the two faces that swapped into view by rotating the die about the A-B edge.
  4. Since C and D never appear together in any single view, and the rotation that revealed D removed C from sight entirely, C and D are opposite faces.
EasyATC Pattern
If two faces of a cube are seen together in the same view, what can be concluded about them?
A single view can only show three mutually adjacent faces meeting at one corner. Seeing two faces together always rules out the possibility that they are opposite.
ModerateATC Pattern
Two views of the same die both show faces marked X and Y. The first view's third face is Z, and the second view's third face is W. What can be concluded?
X and Y are the two common faces across both views, so the two faces that differ, Z and W, are the pair deduced to be opposite by the shortcut rule.
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Subtopic 3

Painted cubes cut into smaller cubes

A large cube is painted on all six outer faces, then cut into many identical smaller cubes. The question asks how many of the small cubes have a given number of painted faces.

The four counting formulas

For a cube cut into n × n × n smaller cubes (n ≥ 2):
3 painted faces (corners): always 8
2 painted faces (edges, not corners): 12(n − 2)
1 painted face (centre of a face): 6(n − 2)²
0 painted faces (fully inside): (n − 2)³

These four counts always add up to exactly n³, the total number of small cubes, which is a quick way to check your working.

8corners3 faces painted
12(n-2)edges2 faces painted
6(n-2)²faces1 face painted
(n-2)³inside0 faces painted
Figure 14.3 — A 4×4×4 painted cube, exploded A large cube made of 64 smaller cubes shown pulled slightly apart, with the 8 corner cubes highlighted in one colour, the edge cubes in a second colour, the face-centre cubes in a third colour, and the fully interior cubes in a fourth colour, to show all four categories at once. Upload image here
Memory trick — "Corners are always 8, everything else uses (n − 2)"

Every cube, whatever its size, has exactly 8 corners. The other three formulas all depend on how much of the cube's edge length remains once the two ends touching a painted face are set aside, which is where the (n − 2) term comes from.

Worked example

A cube is painted on all faces and then cut into 64 identical smaller cubes. How many of the smaller cubes have exactly two painted faces?

  1. 64 small cubes means n³ = 64, so n = 4.
  2. Two painted faces corresponds to an edge cube, using the formula 12(n − 2).
  3. Substituting n = 4 gives 12 × (4 − 2) = 12 × 2 = 24.
  4. As a check: corners = 8, edges = 24, faces = 6 × 2² = 24, inside = 2³ = 8. The total is 8 + 24 + 24 + 8 = 64, which matches the original cube exactly.
EasyATC Pattern
A painted cube is cut into 27 identical smaller cubes. How many of them have exactly three painted faces?
The number of corner cubes, which have three painted faces, is always exactly 8, regardless of the total number of smaller cubes.
ModerateATC Pattern
A painted cube is cut into 27 identical smaller cubes. How many have exactly one painted face?
Since 27 = 3³, n = 3. Using 6(n − 2)² = 6 × 1² = 6.
HardATC Pattern
A painted cube is cut into 125 identical smaller cubes. How many have no painted face at all?
Since 125 = 5³, n = 5. Using (n − 2)³ = 3³ = 27.
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Exam strategy

Five tips that hold in the AAI ATC hall

Standard means numbered 1–6The sum-to-seven rule never applies to letters or symbols.
Seen together, never oppositeThe single most useful fact for any multi-view dice question.
Two common faces, one pair revealedThe fastest shortcut once you spot it.
Find n firstTake the cube root of the total small cubes before applying any formula.
Corners are always 8True for every cube size, with no calculation needed.
Check your totalThe four counts should always add back up to n³.
Quick revision

Chapter summary sheet

Standard dieOpposite faces sum to 7: 1–6, 2–5, 3–4.
Core dice ruleFaces seen together in one view are never opposite.
Two-common-faces shortcutThe two differing faces across two views are opposite.
Corner cubesAlways 8, whatever the cube's size.
Edge cubes12(n − 2), two painted faces each.
Face cubes6(n − 2)², one painted face each.
Inside cubes(n − 2)³, no painted faces.
CheckAll four counts sum to exactly n³.

↓ Free download — Cubes and Dice question PDF

Practice covering the standard dice rule, opposite faces from multiple views, and painted cube cutting with worked numeric answers. Print it, solve it, keep it.

End of chapter

Comprehensive assessment

Multiple choice questions, building in difficulty. Full solutions are in the downloadable PDF above.

Multiple choice questions

1. On a standard die, what is the face opposite the one showing 4?
2. Does the sum-to-seven rule apply to a die marked with letters instead of numbers?
3. If two faces of a cube appear together in one view, can they be opposite each other?
4. Two views of a die share two common faces. What can be said about the two faces that differ?
5. A painted cube is cut into 8 identical smaller cubes. How many have three painted faces?
6. A painted cube is cut into 64 identical smaller cubes. How many have exactly one painted face?
7. A painted cube is cut into 27 identical smaller cubes. How many have no painted face?
8. A painted cube is cut into 125 identical smaller cubes. How many have exactly two painted faces?
9. Why do the four cube-cutting counts always add up to n³?
10. What is the first step in solving any painted-cube counting question?
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Three opposite pairs, four formulas — the whole chapter fits on one page.

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