Introduction
Simplification and Approximation questions form the opening, highest-volume section in almost every
banking exam (IBPS PO/Clerk, SBI PO/Clerk, RRB) — usually 10-15 questions that must be solved in under a
minute each. Speed and a fixed order of operations matter more here than in any other topic.
BODMAS / VBODMAS Rule
| Letter | Operation |
|---|
| V | Vinculum (bar/line — solve what's under it first) |
| B | Brackets — ( ), { }, [ ] in that order |
| O | Of (percentage/fraction "of" a number) |
| D | Division |
| M | Multiplication |
| A | Addition |
| S | Subtraction |
💡 Golden Rule: "Of" is always solved before Division and Multiplication, even though it appears after them alphabetically in "BODMAS" — this trips up candidates who solve strictly left to right instead of by operation priority.
Q. Simplify: 15 + 3 of 4 ÷ 2 − 5
"Of" first: 3 of 4 = 12
Division: 12 ÷ 2 = 6
15 + 6 − 5 = 16
Q. Simplify: [18 − {2 × (5 + 3)} ÷ 4]
Innermost bracket: 5+3=8
{ }: 2×8=16
Division: 16÷4=4
[ ]: 18−4 = 14
Fraction ↔ Percentage Conversion Table — Memorise Cold
💡 Highest-Value Table in This Chapter: Knowing these conversions instantly (without calculating) is the single biggest speed multiplier for both Simplification and Approximation questions.
| Fraction | % | Fraction | % |
|---|
| 1/2 | 50% | 1/8 | 12.5% |
| 1/3 | 33.33% | 1/9 | 11.11% |
| 2/3 | 66.67% | 1/11 | 9.09% |
| 1/4 | 25% | 1/12 | 8.33% |
| 1/5 | 20% | 1/16 | 6.25% |
| 1/6 | 16.67% | 1/20 | 5% |
| 1/7 | 14.28% | 1/25 | 4% |
Squares, Cubes, and Square Roots — Memorise Up To These Ranges
| Range | Recommendation |
|---|
| Squares | 1² to 30² memorised |
| Cubes | 1³ to 20³ memorised |
| Square roots | Perfect squares up to 30² recognised instantly |
Approximation — Core Technique
Flowchart — Approximation Approach
Round EVERY number in the expression to the nearest convenient value (whole number, nearest 10, or nearest 100)
↓
Solve using BODMAS with the rounded values
↓
Match the result to the CLOSEST option (exact match is rarely expected/required)
Q. Approximate the value of: 24.98% of 450.02 + 39.89
Round: 25% of 450 + 40
25% of 450 = 112.5
112.5 + 40 = ≈ 152 or 153 (match to the closest given option)
Q. Approximate the value of: (215.02 × 4.98) ÷ 9.97
Round: (215 × 5) ÷ 10 = 1075 ÷ 10 = ≈ 107.5 (match to the closest option)
Rounding Direction — When It Matters
⚠️ Common Trap: When multiple numbers in an expression are each rounded up OR each rounded down consistently, small errors can compound across a long expression — if two close-looking options remain after approximation, redo the calculation with slightly less aggressive rounding on just the largest term.
Surds and Indices — Quick Rules
| Rule |
|---|
| aᵐ × aⁿ = aᵐ⁺ⁿ |
| aᵐ ÷ aⁿ = aᵐ⁻ⁿ |
| (aᵐ)ⁿ = aᵐⁿ |
| a⁰ = 1 (for any a ≠ 0) |
| a⁻ⁿ = 1/aⁿ |
✅ Exam Focus: VBODMAS order with "of" before division/multiplication · Fraction-percentage conversion table memorised cold · Squares/cubes/roots recall speed · Round-then-solve approximation technique · Surds and indices basic rules.