Basic Mathematics and Quantitative Reasoning
Basic Mathematics and Quantitative Reasoning tests arithmetic and its application: percentages, ratios, averages, simple interest, work rates, speed, and number series. The exam favors short, clean calculations.
Core rules
- Follow BODMAS: brackets, orders, division and multiplication (left to right), addition and subtraction (left to right).
- Percentage change = (change ÷ original) × 100.
- Average = sum of values ÷ number of values.
- Simple interest = principal × rate × time ÷ 100.
- For work rates, add rates: if A finishes in 10 days and B in 15, together they finish in 1 ÷ (1/10 + 1/15) days.
Worked example
A alone takes 10 days and B alone takes 15 days. Their one-day work is 1/10 + 1/15 = 3/30 + 2/30 = 5/30 = 1/6. The reciprocal is 6, so together they take 6 days. Never average 10 and 15 to get 12.5; that is a common error.
Traps
- Adding times instead of adding rates.
- Using the new value as the denominator in a percentage decrease.
- Confusing percentage points with percent.
- Ignoring unit conversions (minutes to hours).
- Rounding too early in a multi-step problem.
Number series often use squares, primes, or alternating patterns, so test those before assuming a simple difference.