10.5: Reverse Alphabet Substitution

 

10.5: Reverse Alphabet Substitution

Letters are replaced by their counterparts in the reverse alphabet (A Z, B Y, ..., Z A).

Problems and Solutions

Problem 1: Replace each letter in "CAT" with its reverse alphabet letter.
Solution:

• Step 1: Reverse alphabet: A=1 → Z=26, B=2 → Y=25, ..., Z=26 → A=1. Rule: n → 27-n.
• Step 2: Letters: C=3, A=1, T=20.
• Step 3: Apply:
  • C: 27-3 = 24 → X
  • A: 27-1 = 26 → Z
  • T: 27-20 = 7 → G
• New word: XZG.
  Explanation: Each letter is replaced by its reverse alphabet counterpart.

Problem 2: What is the reverse alphabet code for "DOG"?
Solution:

• Letters: D=4, O=15, G=7.
• Apply n → 27-n:
  • D: 27-4 = 23 → W
  • O: 27-15 = 12 → L
  • G: 27-7 = 20 → T
• New word: WLT.
  Explanation: Transform each position using 27-n.

Problem 3: Transform "ZEBRA" using reverse alphabet.
Solution:

• Letters: Z=26, E=5, B=2, R=18, A=1.
• Apply:
  • Z: 27-26 = 1 → A
  • E: 27-5 = 22 → V
  • B: 27-2 = 25 → Y
  • R: 27-18 = 9 → I
  • A: 27-1 = 26 → Z
• New word: AVYIZ.
  Explanation: Each letter maps to its reverse position.

Problem 4: Code "KEY" using reverse alphabet.
Solution:

• Letters: K=11, E=5, Y=25.
• Apply:
  • K: 27-11 = 16 → P
  • E: 27-5 = 22 → V
  • Y: 27-25 = 2 → B
• New word: PVB.
  Explanation: Use the reverse alphabet rule.

Problem 5: Transform "SUN" to reverse alphabet.
Solution:

• Letters: S=19, U=21, N=14.
• Apply:
  • S: 27-19 = 8 → I
  • U: 27-21 = 6 → F
  • N: 27-14 = 13 → M
• New word: IFM.
  Explanation: Each letter is replaced by 27-n.

Problem 6: What is the reverse alphabet code for "WXYZ"?
Solution:

• Letters: W=23, X=24, Y=25, Z=26.
• Apply:
  • W: 27-23 = 4 → D
  • X: 27-24 = 3 → C
  • Y: 27-25 = 2 → B
  • Z: 27-26 = 1 → A
• New word: DCBA.
  Explanation: Reverse alphabet transforms high letters to low ones.

Problem 7: Transform "HIJ" using reverse alphabet.
Solution:

• Letters: H=8, I=9, J=10.
• Apply:
  • H: 27-8 = 19 → S
  • I: 27-9 = 18 → R
  • J: 27-10 = 17 → Q
• New word: SRQ.
  Explanation: Each letter maps to 27-n.

Problem 8: Code "BALL" using reverse alphabet.
Solution:

• Letters: B=2, A=1, L=12, L=12.
• Apply:
  • B: 27-2 = 25 → Y
  • A: 27-1 = 26 → Z
  • L: 27-12 = 15 → O
  • L: 27-12 = 15 → O
• New word: YZOO.
  Explanation: Use the reverse alphabet rule.

Problem 9: Transform "QUIZ" to reverse alphabet.
Solution:

• Letters: Q=17, U=21, I=9, Z=26.
• Apply:
  • Q: 27-17 = 10 → J
  • U: 27-21 = 6 → F
  • I: 27-9 = 18 → R
  • Z: 27-26 = 1 → A
• New word: JFRA.
  Explanation: Each letter is replaced by its reverse counterpart.

Problem 10: What is the reverse alphabet code for "MOON"?
Solution:

• Letters: M=13, O=15, O=15, N=14.
• Apply:
  • M: 27-13 = 14 → N
  • O: 27-15 = 12 → L
  • O: 27-15 = 12 → L
  • N: 27-14 = 13 → M
• New word: NLLM.
  Explanation: Transform each letter using 27-n.