Mathematics and Numerical Computation
What this domain tests
Mathematics and Numerical Computation checks whether you can handle arithmetic without a calculator, keep units consistent, and choose the correct operation in practical technical situations. Expect fractions, decimals, percentages, ratio and proportion, averages, simple mensuration, and estimation.
Core rules
- Follow order of operations: brackets, powers/roots, multiplication/division left to right, then addition/subtraction.
- Convert all quantities to the same unit before calculating; write the unit through the working.
- Percentage change uses the original value as the base: change ÷ original × 100%.
- For a reverse percentage, divide by the multiplier, not subtract the percentage from the final value.
- Check reasonableness by rounding to one significant figure.
Worked example
A component is discounted by 20% and then taxed by 10%. The final price is 528. What was the original price? The multipliers chain: 0.80 × 1.10 = 0.88. So 0.88 × original = 528. Original = 528 ÷ 0.88 = 600. Check: 600 less 20% is 480; adding 10% tax gives 48, so the final price is 528. The discount saved 120 and the tax added 48.
Traps
- Adding successive percentages: 20% off then 10% on is not 10% off; multipliers multiply.
- Using the final value as the percentage base.
- Mixing mm and m, or minutes and hours.
- Rounding too early in a multi-step calculation.