Mathematics
The Mathematics section tests arithmetic, algebra, geometry, mensuration, ratio and proportion, percentages and interpreted word problems. Speed matters, but method matters more: most marks are lost through misread units and wrong bases, not through hard mathematics.
Core rules
- Follow BODMAS: brackets, orders/powers, division and multiplication left to right, then addition and subtraction.
- Percentage change uses the original value as the base. A 20% rise followed by a 20% fall does not return to the starting value.
- In ratio problems, convert all quantities to the same unit before forming the ratio.
- Triangle angle sum is 180°; the Pythagorean relation a² + b² = c² applies only to right triangles.
- Circle: area = πr², circumference = 2πr; do not mix radius and diameter.
Worked example
A jacket costs Rs 1,200. It is discounted by 15%, then 5% sales tax is added to the discounted price. Find the final price. Discount = 0.15 × 1200 = 180; discounted price = 1,020. Tax = 0.05 × 1020 = 51; final price = Rs 1,071. The trap is adding 5% to the original Rs 1,200, which gives Rs 1,080 - wrong because tax is charged after the discount.
Traps that cost marks
- Treating “5% off” and “5% of” as the same operation.
- Forgetting to convert metres to centimetres before area calculations.
- Cancelling terms across an equals sign incorrectly in algebra.
- Giving perimeter when the question asks for area, or leaving answers without units.