Reverse, Opposite & Jumbled Codes

🎯 Learning Objective

Recognise reversal, opposite-letter (sum 27) and jumbling patterns beyond simple shifts.

💡 Concept

• Not every code is a shift — also test reversal, opposite letters and jumbling
• Reversal: the word is simply written backwards (PEN → NEP)
• Opposite letters: A↔Z, B↔Y, C↔X … each pair's positions add up to 27
• Opposite of position p = 27 − p (opposite of H(8) is S(19))
• Jumbled codes rearrange letters in a fixed order, e.g. adjacent pairs swap: SIMPLE → ISPMEL
• Identify the rule from the given pair FIRST, only then touch the asked word

🧮 Key Formulas

Opposite pair: position + position = 27

>

Opposite of p = 27 − p

✏️ Easy Example

Q. If PEN is coded as NEP, how is BOOK coded?

1. The code simply reverses the word
2. BOOK written backwards = KOOB

Answer: KOOB

🇮🇳 Real-Life Example

Fold an alphabet strip in half — A lands on Z, B on Y, M on N. Like seats counted from the two gates of a 26-seat coach row: the two numbers always add up to 27.

📝 Exam-Level Example

Q. In a certain code, HOT is written as SLG. How is COLD written in that code?

1. H(8)→S(19): 8 + 19 = 27 — opposite letters
2. C(3)→X(24), O(15)→L(12), L(12)→O(15), D(4)→W(23)

Answer: XLOW

📝 Exam-Level Example

Q. If SIMPLE is coded as ISPMEL, how is MADRAS coded in the same way?

1. SIMPLE → IS-PM-EL: adjacent pairs swapped
2. MA→AM, DR→RD, AS→SA

Answer: AMRDSA

🪄 Memory Trick

Test in order: same letters backwards → reversal. Positions summing to 27 → opposites. Same letters, new order → jumble. New letters, fixed gap → shift.

⚠️ Common Mistakes

• ❌ Using sum 26 instead of 27 for opposite pairs
• ❌ Declaring a reversal after checking only the first and last letters
• ❌ Trying shift maths on a jumbled code where the letters never change

🏆 Exam Tips

• ✅ Memorise opposite pairs in couples: AZ, BY, CX, DW, EV, FU — the rest follow
• ✅ If the code has exactly the same letters as the word, it is a jumble or reversal — never a shift

📌 Summary

• Beyond shifts: reverse, opposite (sum 27), jumble
• Opposite of p = 27 − p
• Same letters in code → jumble or reversal; new letters → shift
• Identify the rule first, apply it second