Numerical Ability
What to master
Numerical Ability covers arithmetic operations, fractions, decimals, percentages, ratio and proportion, averages, number series, basic algebra, measurement, and word problems. Master order of operations (PEMDAS), converting units, and translating words into equations. Know the difference between percentage of, percentage increase/decrease, and percentage points. Practice quick estimation to eliminate impossible choices.
Traps
Common traps are unit mismatches (minutes versus hours), mixing rate and time, averaging speeds by averaging the numbers instead of using total distance over total time, and rounding too early. In percent problems, a 20% increase followed by a 20% decrease does not return to the original value. Watch for “more than” versus “of,” and for series that alternate two patterns. In ratio problems, keep the units matching on both sides of the proportion.
Worked example
A shirt costs ₱800. It is discounted 15%, then another 10% is taken off the sale price. Final price = 800 × 0.85 × 0.90 = ₱612. Do not add the discounts (25%); successive discounts apply to the reduced price. Rule of thumb: for percent change use (new − old) ÷ old × 100.