Primary 5 Maths: Percentage
Percentage is brand new in Primary 5 and appears in every exam after. The conversions to master, the discount trap, and worked examples aligned to the MOE syllabus.
Most schools typically cover this topic in Term 2, around weeks 1–3 — though every school sets its own sequence.
Percentage appears for the first time in Primary 5 — and never leaves. It anchors P6 Percentage, threads through Ratio, and shows up in PSLE data questions. The good news: P5 Percentage is one of the most learnable topics in the syllabus, because it rests on just two ideas — per cent means out of 100, and percentage, fraction and decimal are three ways of writing the same number.
Children who struggle here usually haven't automated the conversions. 45% ↔ 0.45 ↔ 9/20 should take seconds, not working space.
The mistakes to watch for
- Treating % as a unit. Writing "64 %" in an answer that asks for a number of seats. The percentage is an operator on a quantity, not a quantity itself.
- Finding the wrong part. "64% of the seats are occupied — how many are empty?" Many children compute 64% and stop, answering the question they expected instead of the one asked.
- The discount trap. "After a 25% discount, the fan cost $45. Find the original price." Children who compute 25% of $45 have anchored on the wrong whole. The $45 is 75% of the original — reverse percentage questions are the topic's real difficulty step.
- Fraction conversions with awkward denominators. 3/8 as a percentage (37.5%) needs the divide-first habit, not a memorised table.
Example question — finding the complement
Try it: how many are empty?
A school hall has 500 seats. During a concert, 64% of the seats are occupied. How many seats are empty?
Show the worked solution
If 64% are occupied, then 100% − 64% = 36% are empty.
36% of 500 = 36/100 × 500 = 180 seats.
Faster route: 10% of 500 is 50, so 36% is 3.6 × 50 = 180. Same answer, less working.
Try it: reverse percentage
Mr Tan bought a fan for $45 after a 25% discount. What was the original price of the fan?
Show the worked solution
A 25% discount means Mr Tan paid 100% − 25% = 75% of the original price.
75% of the price = $45, so 25% (one-third of 75%) = $15.
Original price = 100% = 4 × $15 = $60.
Check: 25% of $60 is $15 off → $45 paid. ✓
How to practise this topic
Percentage rewards little-and-often practice more than most topics, because the conversions need to become reflexes. Mix question directions deliberately — find the part, find the whole, find the percentage — so your child reads the question instead of pattern-matching the last one they did. And revisit it after a break: percentage learned in Term 3 needs to still be there for the year-end exam.
What this topic covers
In the MOE syllabus, Primary 5 Percentage (P5-M-04) includes:
- Concept of percentage
- Converting between percentage and fraction
- Converting between percentage and decimal
- Finding percentage of a quantity
- Percentage word problems
Before this topic
These topics feed into Percentage — if this one wobbles, check them first: Primary 5 Fractions · Primary 5 Decimals.
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