Logical reasoning · lesson 8 of 30 · free

Coding–decoding — Logical reasoning for kids

In a secret code, every word is changed by the same rule. Compare the word with its code letter by letter: did each letter move forward, move back, swap with its opposite (A ↔ Z), or did the word get written backwards?

▶ Watch how it works

Got it? Practise ↓

How to think it through

Letter by letter — “compare each letter with its code to find the rule, then use the same rule”

  1. Write the word above its code and compare each pair of letters.
  2. Find the rule: the same move (+1, −2 …), opposite letters (A ↔ Z, B ↔ Y), or the word reversed.
  3. Apply the same rule to the new word. After Z comes A again.

Use it for: Coding–decoding questions in Olympiads and aptitude tests, and secret-message games with friends.

Worked example: If CAT is written as DBU, how is DOG written in the same code? EPH

  1. C → D, A → B, T → U: each letter moves 1 place forward.
  2. D → E, O → P, G → H.

Check: EPH moved back one place is DOG ✓

▶ 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 8 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 🗝️ Code Cracker badge when you pass — and a certificate when you finish all 10 lessons of Part 1 · Patterns. You can still take the test without signing in.

🖨️ Coding Decoding 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.