SSC Notes / Quantitative Aptitude / Chapter 2
Chapter 2 of 27

Simplification & Approximation

BODMAS rule, fraction and surd simplification, and fast approximation techniques for SSC's calculator-free environment.

📖 ~12 min read 🔢 SSC Quantitative Aptitude

Introduction

Simplification and Approximation questions test speed and accuracy under a strict no-calculator format — every SSC paper has several of these, and mastering the order of operations plus quick estimation is a guaranteed way to bank easy marks fast.

BODMAS / VBODMAS Rule

Flowchart — Order of Operations
Vinculum (bar)
→
Brackets ( ), { }, [ ]
→
Of (%, powers)
Division
→
Multiplication
→
Addition
→
Subtraction

Brackets are always solved innermost-first: ( ) → { } → [ ].

Q. Simplify: 18 ÷ 3 × [4 + (12 − 8)] − 6
Inner bracket: 12 − 8 = 4 → {4 + 4} = 8
18 ÷ 3 × 8 − 6 = 6 × 8 − 6 = 48 − 6 = 42

Fraction Simplification

  • Always find the LCM of denominators before adding/subtracting fractions.
  • To compare fractions quickly, use cross-multiplication instead of finding a common denominator.
Q. Which is bigger: 5/7 or 7/9?
Cross multiply: 5 × 9 = 45, 7 × 7 = 49
Since 49 > 45, 7/9 > 5/7

Approximation — Rounding Strategy

ApproachWhen to Use
Round to nearest whole numberWhen decimals are small (e.g., 24.98 ≈ 25)
Round to nearest 10/100For large numbers in multiplication/division chains
Simplify percentages to fractionse.g., 33.33% ≈ 1/3, 12.5% ≈ 1/8 (see table below)

Percentage-Fraction Conversion Table (memorise these)

FractionPercentage
1/250%
1/333.33%
1/425%
1/520%
1/616.67%
1/812.5%
1/911.11%
1/128.33%
Q. Find the approximate value of: 899.98 ÷ 29.97 × 6.02
Round: 900 ÷ 30 × 6 = 30 × 6 = 180
💡 Exam Tip: In Approximation questions, SSC options are usually spaced far enough apart that rounding to the nearest convenient number gives the exact matching option — don't waste time on precise decimal calculation.
✅ Practice Focus: VBODMAS multi-bracket problems · Cross-multiplication for fraction comparison · The percentage-fraction conversion table (memorise cold) · Smart rounding in approximation questions.

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