Study Material — 22 PYQs (2018–2023) · Concept Notes · Shortcuts
NDA Simplification & Approximation is a frequently tested subtopic — 22 previous year questions from 2018–2023 papers are included below with concept notes, key rules and shortcut tricks.
If (2⁵ × 3⁴ × 5²) ÷ (2³ × 3² × 5) = 2^a × 3^b × 5^c, then find the value of (a + b + c).
Exam Q 212023Previous Year Pattern
If 40% of a number is 240, and 60% of another number is 360, then what is the ratio of the first number to the second number?
Exam Q 222023Previous Year Pattern
Simplify: (√625 × ∛216) ÷ (√144 + √169) + 5²
Concept Notes
Simplification & Approximation— Rules & Concept
💡
Core Concept
Read this first — the foundation of the topic
→Core Concept
Simplification means solving expressions step by step using BODMAS rule. Approximation means finding values close to exact answers using rounding or estimation techniques. Both skills are essential for solving complex problems in limited exam time
→Follow BODMAS strictly
Brackets, Orders (powers/roots), Division, Multiplication, Addition, Subtraction
2. Simplify fractions by finding common factors
3. Convert mixed numbers to improper fractions when needed
4. Use algebraic identities wherever possible
Approximation Techniques:
1.
Round numbers to nearest 10, 100, or simple fractions
2. Use estimation for quick elimination of wrong options
3. Apply percentage approximations for decimal calculations
🔢
Formula Block
Memorise — at least one formula appears in every paper
Add approximated values
25 + 38 = 63
Exact calculation gives 62.98, so approximation is highly accurate
⚡Mega Shortcut - Options Elimination
In MCQs, approximate the answer first. Eliminate options that are far from your approximation. Then calculate precisely only for remaining close options.
The #1 Most Common Trap: Students ignore BODMAS order and calculate left to right. For expression 2 + 3 × 4, wrong approach gives (2 + 3) × 4 = 20
→Correct answer following BODMAS
2 + (3 × 4) = 14. This single mistake can cost 2-4 marks in the exam.
Another critical error is incorrect fraction handling. When adding fractions with different denominators, students often add numerators and denominators separately instead of finding LCM first.