Primary 5 covers multiplying and dividing decimals up to 3 decimal places by 10, 100, 1000 and their multiples without a calculator, and converting measurements between units in decimal form.
What decimals actually asks of a Primary 5 student
Multiplying by ten moves every digit one place to the left. Teaching it as “move the decimal point” works but hides what is happening, and it breaks down when children try to explain why.
The practical payoff is measurement conversion. Changing 2.35 km to metres is multiplying by 1000, and once that connection is made the conversions stop being facts to memorise.
Multiples such as 200 or 3000 add a step: multiply by the digit, then by the power of ten.
What the syllabus covers
Under the MOE primary mathematics syllabus, decimals at Primary 5 covers:
- multiplying and dividing decimals (up to 3 decimal places) by 10, 100, 1000 and their multiples without calculator
- converting a measurement from a smaller unit to a larger unit in decimal form, and vice versa, for kilometres and metres, metres and centimetres, kilograms and grams, and litres and millilitres
Where the marks actually go
Moving the point the wrong way, so dividing makes the number larger.
Moving the wrong number of places, particularly with 1000 or with multiples.
Converting measurements in the wrong direction, which the decimal form makes harder to spot than whole-number conversion did.
How to practise this properly
Ask whether the answer should be bigger or smaller before touching the point. That single question prevents almost every directional error.
For multiples, split the calculation: × 200 is × 2 then × 100.
Tie every conversion to the underlying factor rather than to a remembered rule — kilometres to metres is × 1000 because there are 1000 metres in a kilometre.
Estimate the size of the answer in whole units first, so a misplaced point becomes obvious.
What this leads to
Percentage, rate and later ratio work all use these conversions inside multi-step problems, and secondary standard form is the same idea extended.
It is also why a difficulty in one year is so often a leftover from an earlier one. Because our curriculum spans Primary 1 through Primary 6, we can go back to the genuine cause rather than treating the symptom in front of us. A child struggling with Primary 5 fractions frequently has a Primary 3 equivalence problem, and no amount of Primary 5 practice will resolve it.
What lessons at Odyssey are actually like
Here is a student talking about what studying with us is actually like. She is at secondary level; the teaching method is the one we use throughout, adjusted to the age. More are on Odyssey Math TV.
Getting help with this topic
We teach Primary 5 maths in small classes at Hexacube, 160 Changi Road #01-02, about three minutes from Eunos MRT. You can see our class schedules and fees, read about our math tutors, or look through the primary school math tuition programme as a whole. If your child is in a nearby school, our primary school directory may be useful too.
Start with the free trial lesson. We use it to work out where the difficulty really sits, and we will say so plainly — including if we think the sensible course is to wait a term and watch. Parents generally find that more useful than a confident sales answer. Get in touch or WhatsApp +65 8512 6882.
What we describe here comes from teaching this syllabus in our own classes since 2012. It is not a forecast for any individual child: progress is produced jointly, by a student willing to do the work with support at home. We do not promise grades. Topics follow the MOE primary mathematics syllabus — check the current syllabus on the MOE website for the definitive version, and see our curriculum page for how we teach it.
Frequently asked questions
Which way does the point move?
Multiplying makes the number larger, so digits move left relative to the point; dividing makes it smaller. Asking bigger or smaller first is the reliable check.
How do you multiply by a multiple like 300?
Split it: multiply by 3, then by 100.
Which measurement conversions are covered?
Kilometres and metres, metres and centimetres, kilograms and grams, and litres and millilitres, in decimal form.
Is a calculator allowed?
No, the syllabus specifies these without a calculator.
