Quant Cheat Code: 20 Must-Know Shortcuts & Formulas

1 Percentage Trick:
A% of B = B% of A
Example: 25% of 40 = 40% of 25 = 10

2 Time & Work:
If A = 10 days, B = 15 days → Together = (10×15)/(10+15) = 6 days

3 Speed, Time, Distance:
Always convert km/h to m/s: ×5/18
e.g., 72 km/h = 72 × 5/18 = 20 m/s

4 Divisibility by 11:
(Sum of digits at odd places) – (Sum at even places) = 0 or multiple of 11
e.g., 121 → (1+1) – 2 = 0 → divisible by 11

5 Squares to Memorize:
1²=1, 2²=4, ..., 25²=625

6 Cubes to Memorize:
1³=1, 2³=8, ..., 15³=3375

7 Profit & Loss:
Profit % = (Profit/CP) × 100
Loss % = (Loss/CP) × 100

8 Simple Interest:
SI = (P × R × T)/100

9 Compound Interest:
A = P(1 + R/100)^T

10 Average Speed (equal distance):
= (2 × S1 × S2) / (S1 + S2)

11 Pipes & Cisterns:
Same as Time & Work — filling = positive, emptying = negative

12 Ratio & Proportion:
If A:B = 2:3, B:C = 4:5 → A:B:C = 8:12:15 (make B same)

13 Algebra Identity:
(a + b)² = a² + 2ab + b²

14 Geometry: Triangle Area:
= ½ × base × height

15 Circle: Area & Circumference:
Area = πr², Circumference = 2πr

16 Data Interpretation Tip:
Always read the question first, then look at the graph/table.

17 DI: Percentage Calculation:
Part/Whole × 100 → round numbers for approximation

18 Number Series: Look for patterns:
+, –, ×, ÷, squares, cubes, alternate series

19 LCM & HCF:
Product of two numbers = LCM × HCF

20 Mixtures & Alligation:
(Cheaper quantity) : (Dearer quantity) = (d – m) : (m – c)