Quantitative aptitude for SSC CGL: strategy and weightage

Ask SSC CGL toppers where their rank came from, and many will point to maths. It is not that they were naturally gifted; many describe themselves as average at school. What they did differently was to treat quantitative aptitude as a skill to be trained — concepts first, then practice, then speed — rather than a talent you either have or don't. This post lays out that approach.

How much maths is worth

Together with reasoning, maths makes up Section I of Tier 2 — 180 marks where preparation pays off reliably.

Topic priorities

The order of study

1. Number system and simplification — calculation fluency.
2. Percentage — the base for profit–loss, interest and DI.
3. Ratio, averages, mixtures.
4. Profit–loss–discount, interest.
5. Time–work, time–speed–distance.
6. Algebra.
7. Geometry, then mensuration.
8. Trigonometry and heights–distances.
9. Data interpretation and statistics.

This order builds each topic on the one before.

Three stages for every topic

Stage 1: concept

Learn why a formula works, not just the formula. For example, understand that a 20% increase followed by a 20% decrease leaves you at 96% of the original, because 1.2 × 0.8 = 0.96. Once you understand this, many "trick" questions become obvious.

Stage 2: practice

Solve 50–100 questions per topic from a standard book and previous years' papers, without a timer at first.

Stage 3: speed

Practise timed sets — 20 questions in 15 minutes — and look for shortcuts.

Speed techniques

• Tables and squares: know squares up to 30, cubes up to 15, and fraction–percentage equivalents (1/8 = 12.5%, 1/6 ≈ 16.67%).
• Use the options: substitute, check divisibility, or eliminate by approximation.
• Assume values: in algebra and percentages, assume convenient numbers (such as 100).
• Approximation in DI and simplification.

A worked example

If x + 1/x = 4, find x² + 1/x².

Square both sides: x² + 2 + 1/x² = 16, so x² + 1/x² = 14. With practice, questions like this take under 20 seconds — which is why algebra is so valuable in CGL.

Formula sheets and error logs

• Keep one page per area with formulas, properties and standard results.
• Keep an error log: each mistake with the correct method.
• Revise both weekly.

If maths has always been your weak point

• Start with NCERT Class 8–10 chapters on the relevant topics.
• Spend the first month on arithmetic only, building confidence.
• Practise 30 minutes of calculation daily — multiplication, division, fractions.
• Don't skip geometry and trigonometry; start them slowly in the second month.
• Measure progress in accuracy first, speed second.

Practice

1. If a price rises by 25% and then falls by 20%, what is the net change?
2. If x − 1/x = 3, find x² + 1/x².
3. What is 3/8 as a percentage?
4. List the nine areas above and rate your confidence in each from 1 to 5. Start with the lowest-rated area that comes early in the study order.

Answers: 1. No change (1.25 × 0.8 = 1). 2. 11. 3. 37.5%.