Decimals and Fractions — RRB NTPC Study Notes
Overview
Decimals and fractions form the backbone of arithmetic computation in RRB NTPC exams. Expect 3–5 direct questions from this topic, plus its application in percentage, ratio, time-and-work, and data interpretation problems. Mastery here means speed and accuracy — a strong candidate converts between forms instinctively and performs operations without hesitation.
The syllabus demands fluency in interconversion (fraction ↔ decimal), all four arithmetic operations on both forms, simplification of complex expressions, and comparison of fractional/decimal quantities. Most errors stem from misplaced decimal points, incorrect denominator handling, and careless simplification. Treat this topic as foundational: once solid, it accelerates every other quantitative section.
Questions range from straightforward computation ("What is 0.125 + 3/8?") to multi-step word problems involving money, measurements, or mixture. The key is recognising when to keep numbers as fractions (for exact answers) versus decimals (for quick approximation).
Key Concepts
- **Fraction representation**: A fraction a/b represents division of a by b. The numerator (a) is the part; denominator (b) is the whole. Proper fraction: a < b. Improper fraction: a ≥ b. Mixed number: whole number + proper fraction (e.g., 2 3/4).