Mathematics: Estimate, Label, Then Solve
What the Mathematics test measures
The test spans four strands. Number and quantity includes fractions, decimals, percents, integers, order of operations, exponents, ratios, proportions, and rates. Algebra includes evaluating and simplifying expressions, solving linear equations and inequalities, and interpreting slope and graphs. Geometry and measurement includes perimeter, area, volume, angle relationships, similar figures, the Pythagorean theorem, and unit conversion. Data and statistics includes mean, median, mode, range, reading tables and graphs, and simple probability.
Traps that cost points
- Answers built from one missed step, such as forgetting to distribute a negative sign.
- Percent of versus percent change; mixing them gives a plausible wrong choice.
- Confusing greatest common factor with least common multiple.
- Using the wrong formula, such as perimeter when area is requested.
- Ignoring units, or failing to convert minutes to hours or inches to feet before calculating.
- Rounding in the middle of a problem and drifting from the exact answer.
Rule of thumb
Estimate first, write the units beside your work, and use part = percent x whole for percent-of problems. For percent change, divide the amount of change by the original amount.
Worked example
A jacket costs $80, is marked down 25%, then 8% tax is added. Discount: 80 x 0.25 = 20, so the price is $60. Tax: 60 x 0.08 = 4.80. Total: $64.80. The trap answer, $66.40, comes from charging tax on the original $80 instead of the sale price.