Kilometres
When distances are very long — like the distance between two cities, or from your home to school — we use kilometres (km). A kilometre is much bigger than a metre.
In Class 3, you learn what a kilometre is, how to convert between km and m, and how to solve word problems about long distances.
What is Kilometres - Class 3 Maths (Measurement)?
A kilometre (km) is a unit of length used for measuring long distances.
1 kilometre = 1000 metres | 1 km = 1000 m
The word "kilo" means 1000. So kilometre literally means 1000 metres.
Kilometres Formula
km to m → × 1000 | m to km → ÷ 1000
Types and Properties
Examples of distances in km:
| Distance | Approximate Value |
|---|---|
| Home to nearby school | 1-2 km |
| One side of a city | 10-20 km |
| Bengaluru to Mysuru | about 150 km |
| Delhi to Agra | about 230 km |
| Mumbai to Pune | about 150 km |
Solved Examples
Example 1: Convert km to m
Question: Convert 3 km to m.
Think:
- 1 km = 1000 m
- 3 km = 3 × 1000 = 3000 m
Answer: 3 km = 3000 m.
Example 2: Convert m to km
Question: Convert 5000 m to km.
Think:
- 5000 ÷ 1000 = 5
Answer: 5000 m = 5 km.
Example 3: Mixed Units
Question: Express 2 km 400 m in metres only.
Think:
- 2 km = 2000 m
- 2000 + 400 = 2400 m
Answer: 2 km 400 m = 2400 m.
Example 4: m to km and m
Question: Express 3750 m in km and m.
Think:
- 3750 ÷ 1000 = 3 remainder 750
- 3 km and 750 m
Answer: 3750 m = 3 km 750 m.
Example 5: Word Problem — Travel
Question: Aman's family drives 12 km to reach the market and 12 km to come back. What is the total distance?
Think:
- 12 + 12 = 24 km
Answer: Total distance = 24 km.
Example 6: Addition with km and m
Question: Priya walks 1 km 600 m in the morning and 2 km 500 m in the evening. Total distance?
Think:
- km: 1 + 2 = 3 km
- m: 600 + 500 = 1100 m = 1 km 100 m
- Total: 3 + 1 = 4 km 100 m
Answer: Total = 4 km 100 m.
Example 7: Subtraction with km and m
Question: The distance from home to school is 3 km. Ria has walked 1 km 800 m. How much is left?
Think:
- 3 km = 3000 m
- 1 km 800 m = 1800 m
- 3000 − 1800 = 1200 m = 1 km 200 m
Answer: 1 km 200 m is left.
Example 8: Choose the Right Unit
Question: Which unit — cm, m, or km — would you use to measure the distance from Delhi to Jaipur?
Think:
- This is a very long distance (about 280 km).
- Metres would give a huge number (280,000 m).
Answer: Use kilometres (km).
Example 9: Comparing Distances
Question: Which is longer: 2 km or 2500 m?
Think:
- 2 km = 2000 m
- 2500 m > 2000 m
Answer: 2500 m is longer.
Key Points to Remember
- 1 km = 1000 m.
- "Kilo" means 1000.
- Use km for long distances (between cities, to school, etc.).
- To convert km to m, multiply by 1000.
- To convert m to km, divide by 1000.
- For addition and subtraction, convert to the same unit first.
- If metres exceed 1000, regroup into km and m.
Practice Problems
- Convert 6 km to m.
- Convert 8000 m to km.
- Express 4 km 250 m in metres only.
- Express 5800 m in km and m.
- Dev walks 2 km 300 m and then runs 1 km 700 m. What is the total distance?
- Which is longer: 3 km or 2800 m?
- The distance from school to the park is 1 km 500 m. From park to home is 2 km 300 m. Total distance from school to home via the park?
Frequently Asked Questions
Q1. What is a kilometre?
A kilometre is a unit of length equal to 1000 metres. It is used to measure long distances like the distance between cities.
Q2. How many metres are in 1 km?
There are 1000 metres in 1 kilometre.
Q3. When should I use km instead of m?
Use km when the distance is very long, like the distance between towns or the length of a road trip. If the distance is hundreds of metres or less, use m.
Q4. How do I convert km to m?
Multiply by 1000. For example, 4 km = 4 × 1000 = 4000 m.
Q5. How do I convert m to km?
Divide by 1000. For example, 7000 m = 7000 ÷ 1000 = 7 km.
Q6. What does 2 km 500 m mean?
It means 2 full kilometres plus 500 extra metres. In metres only: 2000 + 500 = 2500 m.
Q7. What is the relationship between cm, m, and km?
1 km = 1000 m and 1 m = 100 cm. So 1 km = 100,000 cm.
Q8. Is this topic covered in NCERT Class 3?
Yes. NCERT Class 3 Maths introduces the kilometre as a unit for long distances and covers conversion between km and m.
