Mathematics
What the questions test
The math section covers number and operations (fractions, decimals, ratios, proportions, percent), basic algebra (solving linear equations, slope, systems of two equations), geometry (perimeter, area, angles, the Pythagorean theorem), measurement and unit conversion, and data (mean, median, mode, range, simple probability). Most items are multi-step, so a single arithmetic slip costs the point.
Traps to watch
- Percent change. Percent increase is the amount of change divided by the original value. Going from 40 to 50 is a 25% increase (10/40), not 20%.
- Percent of vs. percent off. "20% of 60" is 12; "20% off 60" is 48.
- Order of operations. Parentheses, exponents, multiply/divide left to right, then add/subtract left to right.
- Area vs. perimeter. Area is squared units (length × width); perimeter is linear units added around the outside.
- Units. Check whether the question asks for minutes, not hours, or centimeters, not meters.
- Mean vs. median. Outliers drag the mean; the median resists them.
Rule of thumb
Estimate the answer first, then compute, then plug your result back into the original equation. If the estimate and the computation disagree, recheck the setup rather than the arithmetic.
Worked example
A jacket originally priced at $42 is discounted 15%. What is the final price? Discount = 0.15 × 42 = $6.30. Final price = 42 − 6.30 = $23, corrected: $35.70. Estimate check: 15% of about $40 is $6, so roughly $36 - the answer is reasonable.