Logical reasoning · lesson 19 of 30 · free

Cubes and dice — Logical reasoning for kids

Paint a big cube and cut it into small cubes. Corner cubes have 3 painted faces, edge cubes 2, face-middle cubes 1, and the hidden inside cubes none. On a standard dice, opposite faces add up to 7.

▶ Watch how it works

Got it? Practise ↓

How to think it through

Corners, edges, faces, inside — “where a small cube sits tells you how many of its faces are painted”

  1. Find n, the number of small cubes along one edge (27 small cubes → n = 3).
  2. 3 faces: 8 corners. 2 faces: 12 × (n − 2). 1 face: 6 × (n − 2)². No face: (n − 2)³.
  3. Dice: opposite faces add up to 7 (1–6, 2–5, 3–4).

Use it for: Cube and dice questions in Olympiads and aptitude tests, and building 3D sense.

Worked example: A wooden cube is painted on all six faces, then cut into 27 equal small cubes. How many small cubes have exactly two painted faces? → 12

  1. 27 = 3 × 3 × 3, so n = 3 and n − 2 = 1.
  2. Two painted faces: the edge cubes without corners, 12 × 1 = 12.

Check: 8 + 12 + 6 + 1 = 27 cubes in all ✓

▶ Watch it animated

✏️ Practice

Work it out in your head or on paper, type the answer and press Check. Stuck? Press “Show me how”.

Right: 0 · Tried: 0

🏁 Lesson 19 test

20 questions. Check each answer, then go to the next one. Get 16 or more right to pass.

🏅 Sign in with Google to earn the 🎲 Dice Decoder badge when you pass — and a certificate when you finish all 10 lessons of Part 2 · Order and arrangement. You can still take the test without signing in.

🖨️ Cube and Dice Worksheet

✨ Free AI tutor

Ask the AI tutor about this lesson

Why does it work? When should you use it? Ask in English, मराठी or हिंदी.

Sign in with Google to ask Free — 20 questions a day.

👩‍🏫 Logical reasoning classes near you — online or at home

Prefer a real teacher? TalentJR teachers take live online classes anywhere in India and visit homes in selected cities. Tell us what you need and our team will call you with timings and fees.

Live online classesSmall groups or 1:1 with a teacher, from home, any city.
Teacher at homeA TalentJR teacher visits your home (selected cities).
At a centreClasses at a TalentJR partner centre near you, where available.
Badges, certificates & gifts A badge for every lesson you pass, a certificate for every part you finish, plus TalentJR Points for daily practice. Maths Olympiad Reasoning is a big part of maths Olympiads — practise Olympiad questions too.