Unit 10: Aptitude
Master the Math.
Aptitude is 12.5% of the total questions in TNPSC Group 4 and Group 2. Solve faster and smarter with our tools.
Questions in Exam
25
Total Marks
37.5
Syllabus Coverage
100%
Essential Exam Formulas
Quick-reference cheat sheets for high-yield TNPSC Aptitude modules.
Simplification & Percentages
BODMAS rules, percentages, decimals, fractions, and ratio conversions.
BODMAS Order
Bracket ( ), Of, Div (รท), Mul (ร), Add (+), Sub (-) Percentage Increase
Increase % = (Increase Value / Original Value) ร 100 Salary Rule
If A is R% more than B, B is [R / (100 + R)] ร 100 % less than A HCF & LCM
Common factors, common multiples, division methods, and relationship properties.
Fundamental Relation
HCF(a, b) ร LCM(a, b) = a ร b LCM of Fractions
LCM of Numerators / HCF of Denominators HCF of Fractions
HCF of Numerators / LCM of Denominators Simple & Compound Interest
Annual interest rates, principal, accrued amounts, and compound frequency.
Simple Interest (SI)
SI = (P ร T ร R) / 100 Compound Interest (Amount)
A = P ร (1 + R/100)^n Difference for 2 Years
CI - SI = P ร (R / 100)^2 Time & Work
Individual rates, group coordination, pipes, cisterns, and work efficiency.
Combined Work Rate
X & Y together take (X ร Y) / (X + Y) days Efficiency Rule
Work Done = Efficiency ร Time Taken Chain Rule
(M1 ร D1 ร H1) / W1 = (M2 ร D2 ร H2) / W2 Mensuration
2D shapes, 3D solids, surface area, volumes, and geometric measurements.
Circle Area & Circ.
Area = ฯrยฒ, Circ = 2ฯr (ฯ โ 22/7) Sphere Volume & SA
Volume = (4/3)ฯrยณ, Surface Area = 4ฯrยฒ Cylinder Vol & CSA
Volume = ฯrยฒh, Curved SA = 2ฯrh