Chapter Overview

General Mental Ability (सामान्य मानसिक योग्यता) is the most method-driven block of CGPSC Prelims Paper II (CSAT). Series, analogies, puzzles, calendars and clocks need no outside knowledge — only a fixed routine for each question type, practised until it is automatic. Learn the routine once and these questions become the quickest marks in the paper.

What You’ll Learn

By the end of this chapter, you’ll be able to:

Crack number and letter series with a five-step check, and solve analogies and odd-one-out questions by naming the relation
Solve ranking, comparison, grid, counting and painted-cube puzzles with a table or a formula
Find the day of the week for any date using odd days, and spot repeating calendars
Find the angle between clock hands, the times when they meet or oppose, mirror images and the true time on a faulty clock
Answer each standard question type in under a minute

Prerequisites

Before starting this chapter, you should be comfortable with:

Squares up to 25, cubes up to 12, and the primes below 50
Division with remainder, fractions and mixed numbers (Class VIII level)
The arithmetic of Basic Numeracy — percentages and ratios are not needed here, but quick mental calculation is

Learning Path

Follow these topics in order — the first two build pattern-spotting, the last two are formula topics:

graph TD
    A[Squares, cubes, primes] --> B[1. Series and Analogies]
    B --> C[2. Puzzles]
    C --> D[3. Calendars]
    D --> E[4. Clocks]
    E --> F[Quick Revision sheet]
    C -.-> G[Logical Reasoning]
    F --> H[Data Interpretation]

Topics in This Chapter

Topic	Description	Time
Series and Analogies	Number and letter series, wrong-term questions, number/letter/word analogies, odd one out	12 min
Puzzles	Ranking and position, ordering by comparison, grid puzzles, counting puzzles, painted cubes	12 min
Calendars	Odd days, leap years, day of the week for any date, repeating calendars, doomsday shortcut	10 min
Clocks	Angle between hands, coinciding / right-angle / opposite times, mirror images, faulty clocks	10 min
Quick Revision	Every rule and formula from the chapter on one page	5 min

Where the other reasoning topics live

Coding-decoding, blood relations, direction sense, seating arrangements and syllogisms are in Logical Reasoning. The letter-position skills from Series and Analogies carry straight over to coding-decoding.

Where It Is Asked

Paper	How mental ability appears
Prelims Paper II (CSAT)	Objective MCQs on series, analogies, puzzles, calendars and clocks within the “general mental ability” part of the syllabus. 100 questions, 200 marks, 2 hours.
Mains Paper IV (GS-II)	The reasoning-and-mathematics part (Part 2) tests the same skills, where the working — the table, the chain, the odd-day split — counts as well as the answer.

Paper II is qualifying — but you must qualify

Prelims Paper II marks are not added to your merit, but you must cross the minimum qualifying mark set in the current CGPSC notification (check it for your category). Wrong answers carry negative marking of one-third of the question’s marks. Mental ability is one of the safest blocks for crossing the line: the methods are fixed and the answers are exact, so there is rarely a reason to guess.

Mental ability also supports the other CSAT chapters: Logical Reasoning uses the same table-and-chain habits, Data Interpretation rewards the same exact arithmetic, and Decision Making rewards the same calm, step-by-step approach.

Quick Reference

Key Formulas

Concept	Formula / Fact
Series check order	Differences → Ratios → Squares/cubes → Primes → Alternating
Letter positions	EJOTY = 5, 10, 15, 20, 25; opposite letter \( = 27 - \) position
Total in a row	Left \( + \) Right \( - 1 \)
Handshakes / league	\( \frac{n(n-1)}{2} \); knock-out \( n - 1 \)
Painted cube	8 · \( 12(n-2) \) · \( 6(n-2)^2 \) · \( (n-2)^3 \)
Odd days	Ordinary year 1, leap year 2; 100 / 200 / 300 / 400 years → 5 / 3 / 1 / 0
Leap year	Divisible by 4; century years only if divisible by 400
Clock angle	\( \lvert 30H - 5.5M \rvert \)
Hands \( k \) spaces apart	\( (5H \pm k)\times\frac{12}{11} \) min past \( H \)
Mirror image	\( 11{:}60 - \) time

Exam Focus

High-yield: difference-table series, letter series, ranking, painted cubes, day of the week for a date, angle between the hands, mirror images.
Favourite traps: a series rule that fits only two terms, the missing “−1” in ranking, 1900 as a leap year, a frozen hour hand, “24 meetings a day”.
Speed target: each standard question in under 60 seconds — every topic page ends with a timed speed drill.

Start Learning

Ready to begin? Start with the first topic:

→ Series and Analogies