Mathematics: Number, Measurement and Problem Solving
What you must understand
PSLE Mathematics rewards clear thinking more than fast calculation. Make sure you can move confidently between whole numbers, fractions, decimals and percentages, and that you can convert among them without hesitation. You must know the four operations, order of operations, factors and multiples, and rounding. In measurement, learn the relationships for length, mass, capacity, time and money, and the formulas for perimeter, area and volume of rectangles, squares, triangles and cuboids. Geometry questions expect accurate use of angles on a straight line, angles at a point, and properties of triangles and quadrilaterals. For statistics, read tables, bar graphs and line graphs and find the mean, median, mode and range.
Traps to watch for
Word problems often hide information in a second sentence, or give a quantity in different units. Always convert to the same unit before calculating. Questions asking for the remaining amount after several events catch candidates who stop one step early. Percentage questions may ask for the original price after a discount, which needs division rather than subtraction. Fraction questions mixing parts of a whole with parts of a remainder need careful reading. Check whether an answer should be a whole number, for example the number of buses needed, where you must round up rather than down.
Rule of thumb and worked example
Write a one-line plan before calculating: what is given, what is asked, and which operation links them. Show units in every line.
Example: A tank holds 24 litres. A tap fills it at 3 litres per minute, but a leak drains 1 litre per minute. How long to fill it? Net rate = 3 − 1 = 2 litres per minute. Time = 24 ÷ 2 = 12 minutes. Check: in 12 minutes the tap adds 36 litres and the leak removes 12 litres, leaving 24 litres, which matches the tank.