My child mixes up the units. How should I teach this?

Start with the three steps: millimetres to centimetres times 10, centimetres to metres times 100, and metres to kilometres times 1000.

What should be done first in the arithmetic?

Change every length to the same unit before adding or subtracting, so one metre and one centimetre are never added directly.

How long should this paper take?

About 15 minutes; check the answers straight away afterwards.

P3 Maths Length and Distance Paper 1: Basics

2026-11-09

Tutor Prep Guide · P3 Maths

Ten original items, each with an answer and a one-line explanation.

Direct answers　Items 1-3 are basic, 4-6 intermediate and 7-9 challenge, with item 10 as the error review. Time yourself first, then check each answer and redo what is wrong.

01　Paper details (check answers afterwards)

Item	Detail
Questions	10
Suggested time	15
Difficulty mix	Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1
Chapter	Chapter: P3 Maths: Length and Distance
Level	P3

02　Questions (10 items)

FoundationHow many millimetres are there in 3 centimetres?
FoundationHow many centimetres are there in 5 metres?
FoundationWhat is 250 centimetres in metres and centimetres?
IntermediateHow many metres are there in 2 kilometres?
IntermediateA pencil is 18 centimetres long and a cap adds 7 centimetres. What is the total length?
IntermediateHow many centimetres are there in 80 millimetres?
ChallengeA rope is 1 metre 20 centimetres long. After cutting away 45 centimetres, how much is left?
ChallengeA desk is 1 metre 15 centimetres long and a chair is 45 centimetres long. What is the total?
ChallengeSubtract 1 kilometre 800 metres from 4 kilometres 500 metres.
Error redoError review: a pupil wrote 3 metres as 30 centimetres. How many centimetres should it be?

03　Answers and one-line notes

#	Answer	One-line note
1	30 millimetres	One centimetre is 10 millimetres, so 3 centimetres is 3 times 10 = 30 millimetres.
2	500 centimetres	One metre is 100 centimetres, so 5 metres is 5 times 100 = 500 centimetres.
3	2 metres 50 centimetres	Every 100 centimetres is one metre, so 250 centimetres holds two metres with 50 centimetres left.
4	2000 metres	One kilometre is 1000 metres, so 2 kilometres is 2000 metres.
5	25 centimetres	The units are the same, so 18 + 7 = 25 centimetres.
6	8 centimetres	Ten millimetres make one centimetre, so 80 divided by 10 = 8 centimetres.
7	75 centimetres	First change it to 120 centimetres, then 120 minus 45 = 75 centimetres.
8	1 metre 60 centimetres	115 + 45 = 160 centimetres, which is 1 metre 60 centimetres.
9	2 kilometres 700 metres	Change both to 4500 metres and 1800 metres, subtract to get 2700 metres, that is 2 kilometres 700 metres.
10	300 centimetres	One metre is 100 centimetres, so 3 metres is 3 times 100 = 300 centimetres, not 30 centimetres.

04　What to do after marking

After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
Repeat the same item two days later; move to the next paper only when both attempts are correct.
Parents only need the answer and note columns; there is no need to explain every item.

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Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.