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Tamil Nadu (TNBSE)Class 6 Mathematics★ 6-10 marks in the TN Class 6 Term 2 exam through unit and time conversion sums

Measurements (Term 2) - Units and Time

Samacheer Kalvi (TN State Board) Class 6 Maths — Term 2 Chapter 2, Measurements. Converting units of length, mass and capacity, converting between the 12-hour and 24-hour clock, and performing the fundamental operations on quantities given in different units, with worked examples, exercises and quick revision.

⏱ 14 min readEasy difficulty✓ Free · NCERT-aligned

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By the end of this chapter you'll be able to…

1Convert units of length, mass and capacity
2Decide when to multiply or divide
3Convert between 12-hour and 24-hour time
4Add and subtract quantities in mixed units
5Solve time-duration problems

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Why this chapter matters

Converting units and telling time are everyday life skills used in shopping, travel and cooking. Unit and time conversions are directly tested in the TN Class 6 Term 2 exam.

Before you start — revise these

A 5-minute refresher here will save you 30 minutes of confusion below.

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Class 5 — Measurement

Basic units.

Measurements (Units and Time) — Class 6 Maths (Samacheer Kalvi)

TN State Board (Samacheer Kalvi) Class 6 Mathematics, Term 2 — Chapter 2. Converting units and working with time.

1. About this chapter

This chapter covers converting units of length, mass and capacity, time conversion (12-hour and 24-hour clock), and the fundamental operations on quantities with different units.

2. Unit conversion

The metric system uses powers of ten:
- Length: 1 km = 1000 m; 1 m = 100 cm; 1 cm = 10 mm.
- Mass: 1 kg = 1000 g; 1 g = 1000 mg.
- Capacity: 1 L = 1000 mL.
To go to a smaller unit, multiply; to a larger unit, divide. Example: 3 km = 3 × 1000 = 3000 m.

3. Time conversion

1 hour = 60 minutes; 1 minute = 60 seconds; 1 day = 24 hours.
24-hour clock: after 12 noon, add 12 to the hour — 1 p.m. = 13:00, 6 p.m. = 18:00; midnight = 00:00.

4. Operations on different units

To add or subtract quantities, first convert them to the same unit.
Example: 2 m 50 cm + 1 m 70 cm = 250 cm + 170 cm = 420 cm = 4 m 20 cm.

5. Worked examples

Example 1. Convert 5 km 250 m into metres. 5 × 1000 + 250 = 5250 m.

Example 2. Write 9 p.m. in 24-hour time. 9 + 12 = 21:00.

Example 3. Add 1 kg 600 g and 2 kg 800 g. 1600 + 2800 = 4400 g = 4 kg 400 g.

6. Exercises (Samacheer Kalvi)

Convert: (a) 4 m into cm (b) 2500 g into kg and g (c) 3 L into mL.
Write in 24-hour time: (a) 4 p.m. (b) 11:30 a.m.
Subtract: 5 m 20 cm − 2 m 75 cm.
A film starts at 18:15 and runs 2 h 30 min. When does it end?
Add 3 L 400 mL and 1 L 750 mL.

7. Common mistakes

Mistake: Multiplying when converting to a larger unit. Fix: Smaller → larger means divide (and larger → smaller means multiply).
Mistake: Adding quantities in different units directly. Fix: Convert to the same unit first, then add.
Mistake: Forgetting to add 12 for p.m. in 24-hour time. Fix: For p.m. times (after noon), add 12 to the hour.

8. Quick revision

Term 2 · Ch 2 · units and time.
Length: km–m–cm–mm; mass: kg–g–mg; capacity: L–mL (all ×/÷ 10, 100, 1000).
Smaller unit → multiply; larger unit → divide.
Time: 1 h = 60 min, 1 min = 60 s; 24-hour clock adds 12 after noon. Convert to the same unit before adding/subtracting.

Key formulas & results

Everything you need to memorise, in one card. Screenshot this for revision.

Length

1 km = 1000 m, 1 m = 100 cm, 1 cm = 10 mm

Metric system.

Mass / capacity

1 kg = 1000 g; 1 L = 1000 mL

Powers of ten.

Conversion direction

smaller unit → multiply; larger unit → divide

Move the decimal.

Time

1 h = 60 min, 1 min = 60 s; p.m. + 12 = 24-hour

24-hour clock.

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Common mistakes & fixes

These are the exact errors that cost students marks in board exams. Read them once, save yourself the trouble.

WATCH OUT

✗ Multiplying when converting to a larger unit

✓ Smaller → larger means divide (larger → smaller means multiply).

WATCH OUT

✗ Adding quantities in different units directly

✓ Convert to the same unit first, then add.

WATCH OUT

✗ Forgetting to add 12 for p.m. in 24-hour time

✓ For p.m. times (after noon), add 12 to the hour.

NCERT exercises (with solutions)

Every NCERT exercise from this chapter — what it covers and how many questions to expect.

Unit conversion

Convert length, mass and capacity.

Questions

Time conversion

12-hour and 24-hour conversions.

Questions

Operations

Add/subtract mixed-unit quantities.

Questions

Practice problems

Try each one yourself before tapping "Show solution". Active recall > rereading.

Q1EASY· Length

Convert 5 km 250 m into metres.

▶ Show solution

5250 m.

Q2EASY· Time

Write 9 p.m. in 24-hour time.

▶ Show solution

21:00.

Q3MEDIUM· Mass

Add 1 kg 600 g and 2 kg 800 g.

▶ Show solution

4400 g = 4 kg 400 g.

Q4MEDIUM· Length

Subtract 5 m 20 cm − 2 m 75 cm.

▶ Show solution

520 − 275 = 245 cm = 2 m 45 cm.

Q5MEDIUM· Time

A film starts at 18:15 and runs 2 h 30 min. When does it end?

▶ Show solution

18:15 + 2:30 = 20:45.

Q6EASY· Capacity

Convert 3 L into mL.

▶ Show solution

3000 mL.

5-minute revision

The whole chapter, distilled. Read this the night before the exam.

•Term 2 Chapter 2 of Samacheer Kalvi Class 6 Maths.
•Length: 1 km = 1000 m, 1 m = 100 cm, 1 cm = 10 mm.
•Mass: 1 kg = 1000 g; capacity: 1 L = 1000 mL.
•Smaller unit → multiply; larger unit → divide.
•Time: 1 h = 60 min, 1 min = 60 s; the 24-hour clock adds 12 after noon.
•Convert to the same unit before adding or subtracting quantities.

Tamil Nadu (TNBSE) marks blueprint

Where the marks come from in this chapter — so you can plan your prep.

Typical chapter weightage: 6-10 marks across unit and time conversion

Question type	Marks each	Typical count	What it tests
Conversion	1	3-4	Length, mass, capacity, time
Operations	2	2	Add/subtract mixed units
Time duration	2	1	Start/end times

Prep strategy

Memorise the metric relations
Multiply going smaller, divide going larger
Add 12 for p.m. in 24-hour time
Convert to one unit before operating

Where this shows up in the real world

This chapter isn't just an exam topic — it lives in the world around you.

Shopping

Weights and volumes are bought in mixed units.

Travel

Timetables use the 24-hour clock.

Cooking

Recipes need accurate unit conversions.

Exam strategy

Battle-tested tips from teachers and toppers for this chapter.

Write the conversion factor first
Choose multiply or divide by direction
Convert to one unit before operating
Add 12 for p.m. times

Going beyond the textbook

For olympiad aspirants and curious learners — topics that build on this chapter.

A tank holds 2 L 500 mL; how many 250 mL glasses can be filled?
Find the time 3 h 45 min after 22:30.

Where else this chapter is tested

CBSE board isn't the only one — other exams test this chapter too.

TN Class 6 Term 2 ExamHigh

NMMS / Foundation MathsMedium

School unit testsHigh

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Questions students ask

The real ones — pulled from the Q&A community and tutor sessions.

Multiply when changing to a smaller unit (e.g. m to cm) and divide when changing to a larger unit (e.g. g to kg).

Add 12 to the hour for any time after 12 noon — so 3 p.m. becomes 15:00 and 8 p.m. becomes 20:00; a.m. times stay the same (except 12 a.m. = 00:00).

Practice more, ask doubts, find a tutor

Tamil Nadu (TNBSE) Class 6 mock tests

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