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Updated: September 2026 · Based on SSC CGL PYQ analysis (2016–2025)
Simplification looks like a long, scary calculation — but it’s actually the fastest, safest scoring topic in the Quant section, if you do two things: follow BODMAS in the exact right order, and switch on an “approximation mindset” so you stop calculating things the answer options don’t even need. Master those two, plus a short list of values worth memorising, and simplification becomes near-guaranteed marks in seconds each.
Quick answer: Solve every simplification by applying BODMAS / VBODMAS — Vinculum, Brackets, Of, Division, Multiplication, Addition, Subtraction — remembering that Division and Multiplication are done left-to-right, as are Addition and Subtraction. For approximation questions, round every number to the nearest easy value first (49.8 → 50, 24.9% → 25%); the options are spaced far enough apart that the rounded answer is correct. Memorising squares, cubes and fraction-to-percentage values makes the whole topic almost instant.
On this page:
The BODMAS / VBODMAS rule
Every simplification is decided by the order in which you perform the operations. Learn this sequence and never break it:
| Order | Operation |
|---|---|
| V | Vinculum (bar/line) — solve first |
| B | Brackets — in the order ( ) → { } → [ ] |
| O | Of (means multiply, given priority) |
| D | Division |
| M | Multiplication |
| A | Addition |
| S | Subtraction |
The rule everyone forgets: Division and Multiplication sit at the same level, so do them left to right as they appear — not all divisions first. The same goes for Addition and Subtraction.
Example: 12 + 6 ÷ 2 × 3 − 4 = 12 + (6 ÷ 2) × 3 − 4 = 12 + 3 × 3 − 4 = 12 + 9 − 4 = 17.
The BODMAS traps SSC uses
- Doing all divisions before multiplications. They’re equal — go strictly left to right.
- Mishandling “of”. “1/2 of 80” means 1/2 × 80 = 40, done before ordinary division.
- Sign slips with brackets. A minus sign before a bracket flips every sign inside: 10 − (3 − 5) = 10 − (−2) = 12.
- Skipping the innermost bracket. Always resolve ( ) before { } before [ ].
The approximation mindset
Approximation questions are a gift — they tell you not to calculate exactly. The trick is to round every number to the nearest easy value before doing anything, because the answer options are spaced far apart, so the rounded result still lands on the right one.
- Round decimals to whole numbers: 49.8 × 20.2 ≈ 50 × 20 = 1000.
- Round percentages: 24.9% of 1599 ≈ 25% of 1600 = 400.
- Round to nearest perfect square/cube: √624 ≈ √625 = 25.
When NOT to approximate: if the question says “simplify” or “find the exact value,” or if two options are very close together, do the exact calculation. Approximation is only for questions that ask for the approximate value.
Values worth memorising (your speed table)
Most of your time is lost re-deriving basic values. Memorise these once and simplification speeds up dramatically.
Squares (11–30):
| n | n² | n | n² |
|---|---|---|---|
| 11 | 121 | 21 | 441 |
| 12 | 144 | 22 | 484 |
| 13 | 169 | 23 | 529 |
| 14 | 196 | 24 | 576 |
| 15 | 225 | 25 | 625 |
| 16 | 256 | 26 | 676 |
| 17 | 289 | 27 | 729 |
| 18 | 324 | 28 | 784 |
| 19 | 361 | 29 | 841 |
| 20 | 400 | 30 | 900 |
Cubes (1–12):
| n | n³ | n | n³ |
|---|---|---|---|
| 1 | 1 | 7 | 343 |
| 2 | 8 | 8 | 512 |
| 3 | 27 | 9 | 729 |
| 4 | 64 | 10 | 1000 |
| 5 | 125 | 11 | 1331 |
| 6 | 216 | 12 | 1728 |
Fraction ↔ percentage (the biggest time-saver):
| Fraction | % | Fraction | % |
|---|---|---|---|
| 1/2 | 50% | 1/9 | 11.11% |
| 1/3 | 33.33% | 1/10 | 10% |
| 1/4 | 25% | 1/11 | 9.09% |
| 1/5 | 20% | 1/12 | 8.33% |
| 1/6 | 16.67% | 1/15 | 6.67% |
| 1/7 | 14.28% | 1/16 | 6.25% |
| 1/8 | 12.5% | 1/20 | 5% |
These conversions turn awkward percentages into easy fractions instantly — for example, 12.5% of 640 is just 1/8 × 640 = 80, with no long working.
Solved examples
1. Nested brackets: 8 + [ (4 × 5) − { 6 ÷ (1 + 2) } ]
= 8 + [ 20 − { 6 ÷ 3 } ] = 8 + [ 20 − 2 ] = 8 + 18 = 26.
2. Fractions: 2/3 + 3/4 − 1/6 → LCM = 12 → 8/12 + 9/12 − 2/12 = 15/12 = 5/4 (= 1¼).
3. Approximation: 24.96% of 1599.98 + 15.02% of 799.99 ≈ 25% of 1600 + 15% of 800 = 400 + 120 = 520.
4. Square root: √2025 = 45 (since 45² = 2025 — recognising the square saves all the working).
Turn these tricks into exam speed 🎯
Simplification marks come from speed, and speed only comes from timed practice. The Quant section is a fixed 15-minute lock — try a free sectional mock and see how many you can clear in time.
Speed rules
- Read the instruction first. “Approximate value” means round; “simplify” means exact.
- Convert percentages to fractions using the table — it’s almost always faster.
- Spot perfect squares and cubes before reaching for long division of roots.
- Cancel before you multiply in fractions — smaller numbers, fewer errors.
- Go left to right for ÷ and × (and for + and −); never reorder them.
Common mistakes that cost marks
- Breaking the left-to-right rule for division and multiplication.
- Sign errors when a minus sits before a bracket.
- Calculating exactly when the question only wants an approximate value.
- Ignoring “of” or treating it as division instead of multiplication.
- Re-deriving squares and fractions mid-exam instead of memorising them.
Practice mini-set (self-test)
Solve each first, then tap to reveal the answer.
Q1. 15 + 9 ÷ 3 × 2 − 4 = ?
Show answer
17. 9 ÷ 3 = 3; 3 × 2 = 6; 15 + 6 − 4 = 17. (Left to right for ÷ and ×.)
Q2. Approximate value of 34.97% of 800.
Show answer
280. ≈ 35% of 800 = 280.
Q3. √1444 = ?
Show answer
38. 38² = 1444.
Q4. 3/5 + 1/2 − 1/10 = ?
Show answer
1. LCM = 10 → 6/10 + 5/10 − 1/10 = 10/10 = 1.
Q5. 12.5% of 640 = ?
Show answer
80. 12.5% = 1/8, and 1/8 × 640 = 80.
Frequently asked questions
What is the BODMAS rule?
BODMAS (or VBODMAS) is the order for solving any expression: Vinculum, Brackets, Of, Division, Multiplication, Addition, Subtraction. Division and Multiplication are done left to right at the same level, as are Addition and Subtraction.
How do I solve simplification questions quickly?
Apply BODMAS strictly, convert percentages to fractions using memorised values, and recognise perfect squares and cubes instead of calculating them. Memorising a short table of values removes most of the time you’d otherwise lose.
What is the difference between simplification and approximation?
Simplification asks for the exact value using BODMAS. Approximation asks only for a value close to the answer, so you round every number to the nearest easy value first — the options are spaced far enough apart that the rounded result is correct.
Which values should I memorise for simplification?
Squares up to 30, cubes up to about 12, and the fraction-to-percentage conversions such as 1/8 being 12.5 per cent. These come up constantly and save the most time.
Is “of” multiplication or division in BODMAS?
“Of” means multiplication and is given priority, so “1/2 of 80” is 1/2 × 80 = 40, resolved before ordinary division.
Is simplification important for SSC CGL?
Yes. It is among the highest-frequency and highest-accuracy Quant topics, so mastering it secures quick, reliable marks in the 15-minute Quant section.
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