Converting Measurements
Use multiplication and division by 10, 100, and 1000 to convert between units!
1. Key Conversion Facts
📏 Length
- 1 m = 100 cm
- 1 km = 1000 m
⚖️ Mass
- 1 kg = 1000 g
🧪 Volume/Capacity
- 1 ℓ = 1000 ml
💡 The Rule
- Bigger unit → smaller unit: Multiply
- Smaller unit → bigger unit: Divide
2. Length Conversions
Converting metres to centimetres (m → cm)
Rule: 1 m = 100 cm, so multiply by 100
Example: Convert 0.9 m to cm
0.9 m = 0.9 × 100 cm = 90 cm
Example: Convert 3 m 28 cm to cm
3 m 28 cm = 300 cm + 28 cm = 328 cm
Converting centimetres to metres (cm → m)
Rule: 100 cm = 1 m, so divide by 100
Example: Write 285 cm in metres and centimetres
285 cm = 285 ÷ 100 m = 2.85 m
= 2 m 85 cm
Converting between kilometres and metres (km ↔ m)
Rule: 1 km = 1000 m
km → m (multiply by 1000)
1.8 km = 1.8 × 1000 m = 1800 m
m → km (divide by 1000)
4008 m = 4008 ÷ 1000 km = 4.008 km (which is 4 km 8 m)
3. Mass Conversions
Converting kilograms and grams (kg ↔ g)
Rule: 1 kg = 1000 g
Example: Write 5 kg 82 g in grams
5 kg 82 g = 5000 g + 82 g
= 5082 g
Example: Write 3109 g in kilograms and grams
3109 g = 3000 g + 109 g
= 3 kg 109 g
4. Volume/Capacity Conversions
Converting litres and millilitres (ℓ ↔ ml)
Rule: 1 ℓ = 1000 ml
Example: Write 2 ℓ 5 ml in millilitres
2 ℓ 5 ml = 2000 ml + 5 ml
= 2005 ml
Example: Write 4625 ml in litres and millilitres
4625 ml = 4000 ml + 625 ml
= 4 ℓ 625 ml
📌 Conversion Summary
| Type | Conversion | Big unit → small unit | Small unit → big unit |
|---|---|---|---|
| Length | 1 m = 100 cm | × 100 | ÷ 100 |
| Length | 1 km = 1000 m | × 1000 | ÷ 1000 |
| Mass | 1 kg = 1000 g | × 1000 | ÷ 1000 |
| Volume | 1 ℓ = 1000 ml | × 1000 | ÷ 1000 |
Practice Problems
Practice 1: Length Conversion
Write 2 km 315 m in metres.
ShowHide solution
2 km 315 m = 2000 m + 315 m
= 2315 m
Practice 2: Mass Conversion
Convert 14.085 kg to grams.
ShowHide solution
14.085 kg = 14.085 × 1000 g
= 14 085 g
Practice 3: Volume Conversion
Write 7250 ml in litres and millilitres.
ShowHide solution
7250 ml = 7000 ml + 250 ml
= 7 ℓ 250 ml
Practice 4: Decimal Conversion
Convert 3.5 ℓ to millilitres.
ShowHide solution
3.5 ℓ = 3.5 × 1000 ml
= 3500 ml
Key Takeaways
- 1 m = 100 cm and 1 km = 1000 m
- 1 kg = 1000 g
- 1 ℓ = 1000 ml
- Converting from big to small units: Multiply
- Converting from small to big units: Divide
- Use your knowledge of × and ÷ by 10, 100, 1000!