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Quantitative Aptitude / Arithmetic

Percentage & Fraction Conversions

Critical (2-4 questions directly, essential for D.I.)

Concept Overview

Percentages are the absolute foundation of arithmetic. Understanding percentage changes, successive changes, and rapid fraction conversions (e.g., 16.66% = 1/6) is the key to solving questions under 30 seconds without long decimal calculations.

Exam Relevance

Highly tested in SSC CGL, Banking Prelims (Simplification & D.I.), Railways NTPC, and Police Sub-Inspector exams.

Key Formulas & Shortcuts

  • Percentage Increase = (Increase / Original Value) * 100
  • Successive Percentage Change = a + b + (ab / 100)
  • Fraction to Percentage: 1/8 = 12.5%, 1/6 = 16.67%, 1/12 = 8.33%, 1/15 = 6.67%

Common Weaknesses & Mistakes

1

Confusing base values: Calculating increase/decrease on the wrong initial value.

2

Doing long multiplication instead of multiplying by simplified fractions.

3

Successive changes mistake: Adding percentages directly instead of using the successive change formula (a + b + ab/100).

Ready to check your subject readiness?

This will pre-configure your **Quantitative Aptitude Diagnostic Test**. You will bypass selection screens and land directly on the start screen to begin a 40-question subject-level diagnostic test.