Mathematics
What you must know
Expect whole numbers and operations (add, subtract, multiply, divide, with and without regrouping), fractions and decimals, percent, ratio and proportion, measurement (length, mass, time, money), perimeter and area, and word problems. Also review averages, rounding, and order of operations.
Traps to watch
- Operation words: "more than," "in all," "total," "sum" suggest addition; "left," "difference," "how many more" suggest subtraction; "each," "per," "times as many" suggest multiplication; "share equally," "per group" suggest division.
- Units must match before you compute. Convert first: 1 m = 100 cm, 1 kg = 1000 g, 1 hour = 60 minutes.
- In fractions, find a common denominator before adding or subtracting; do not add denominators.
- Percent means "per 100." To find a percent of a number, change it to a decimal and multiply.
- Check by estimating first; if your answer is far from the estimate, redo it.
Worked example
A shirt costs ₱450. It is on sale at 20% off. What is the sale price?
- Step 1: Find the discount: 20% of 450 = 0.20 × 450 = 90.
- Step 2: Subtract: 450 − 90 = ₱360.
- Check: 10% of 450 is 45, so 20% is 90. 450 − 90 = 360. ✔
Rule of thumb
For any word problem, write down what is asked, what is given, and which operation connects them before computing. Most errors come from choosing the wrong operation or forgetting to convert units, not from arithmetic.