How is the error-review paper different from the first three?

It targets conversion and carrying: 100 between m and cm, 1 000 between km and m, and carrying only at 100 cm.

What is a safe way to add lengths?

Convert everything to one unit first, calculate, then write the answer back in mixed units and estimate to check.

P3 Maths Length and Distance Paper 4: Error Review

2026-11-09

Tutor Prep Guide · P3 Maths

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

Direct answers　Items 1-3 revisit the 100 and 1 000 factors in length conversion, 4-6 cover adding mixed units and borrowing, 7-9 apply length subtraction to ropes, planks and walking routes, and item 10 unpicks treating 1 km as 10 m. Cover the answers first, then check each note.

01　Paper details (check answers afterwards)

Item	Detail
Questions	10
Suggested time	20
Difficulty mix	Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1
Chapter	Chapter: P3 Maths Length and Distance
Level	P3

02　Questions (10 items)

FoundationError review: how many centimetres are in 2 m?
FoundationError review: write 350 cm in metres.
FoundationError review: how many metres are in 4 km?
IntermediateError review: write 1 m 25 cm in centimetres only.
IntermediateError review: add 2 m 8 cm and 1 m 45 cm.
IntermediateError review: subtract 1 km 600 m from 5 km.
ChallengeError review: a 3 m 20 cm rope has 85 cm cut off. What is left?
ChallengeError review: 1 m 60 cm is cut from a 4 m plank. How many centimetres remain?
ChallengeError review: Ming walks 1 km 200 m then another 900 m. What is the total?
Error redoError review: a pupil writes 3 km = 30 m. What is wrong and what is correct?

03　Answers and one-line notes

#	Answer	One-line note
1	200 cm	1 m = 100 cm, so 2 m = 200 cm; 20 cm assumes 1 m = 10 cm.
2	3.5 m	100 cm = 1 m, so 350 / 100 = 3.5 m; 35 m divides by 10 only.
3	4000 m	1 km = 1 000 m, so 4 x 1 000 = 4000 m; 40 m treats km as 10 m.
4	125 cm	1 m = 100 cm, so 100 + 25 = 125 cm; 125 m is a unit slip.
5	3 m 53 cm	Add metres to metres and centimetres to centimetres: 3 m and 53 cm; only 100 cm carries over.
6	3 km 400 m	Borrow 1 km as 1 000 m: 5 km − 1 km 600 m = 3 km 400 m; 4 km 400 m forgets the borrow.
7	2 m 35 cm	3 m 20 cm = 320 cm, and 320 − 85 = 235 cm, i.e. 2 m 35 cm; subtracting 20 − 85 goes negative.
8	240 cm	4 m = 400 cm and 1 m 60 cm = 160 cm, so 400 − 160 = 240 cm; 260 cm is a borrow slip.
9	2 km 100 m	1 km 200 m = 1 200 m, and 1 200 + 900 = 2100 m = 2 km 100 m; 1 km 1 100 m never carries.
10	It is 3 000 m, because 1 km = 1 000 m	Kilometres and metres differ by a factor of 1 000, not 10: 3 x 1 000 = 3 000 m.

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.