Reasoning7 min readUpdated 2026-09-15

Coding-Decoding & Number Series: 12 Core Question Archetypes in SSC Reasoning

Stop losing 2 minutes trying to figure out alphabet shifts. Learn the EJOTY framework, reverse letter pairs (AZ, BY, CX), and high-frequency series patterns.

Preparation Guru Academic TeamReasoning & Logic Pedagogy

Alphabet Memorization Frameworks: EJOTY and Reverse Pairs

The biggest time-waster in Reasoning is writing out the alphabet A-Z on your rough sheet before the exam starts. You must know letter positions automatically.

  • EJOTY: E(5), J(10), O(15), T(20), Y(25).
  • C-FILORUX: Table of 3 multiples: C(3), F(6), I(9), L(12), O(15), R(18), U(21), X(24).
  • Reverse Pairs (Sum = 27): A-Z (Azad), B-Y (Boy), C-X (Crux), D-W (Dew), E-V (Evening), F-U (Fun), G-T (GT Road), H-S (High School), I-R (Indian Railway), J-Q (Jungle Queen), K-P (Kurta Pajama), L-O (Love), M-N (Man).
Key Strategy Takeaway

Knowing reverse letter pairs by heart solves 40% of recent SSC coding-decoding questions instantly.

The 4 Main Coding Archetypes

1. Direct Positional Shift (+3, -2, alternating prime shifts).

2. Cross Pattern (First letter codes to last, second to second-last).

3. Reverse Opposite Letter Coding (Letter replaced by its reverse pair equivalent).

4. Vowel-Consonant Segregation (Vowels shifted by +1, Consonants coded by positional rank).

Number Series: Difference of Differences

When an integer sequence appears irregular, take consecutive differences. If the first difference reveals no pattern, take the second difference. Over 70% of complex SSC series reduce to a constant arithmetic difference at the second tier.