Measurement
Length Conversions (km, m, cm)
Length uses kilometres (km), metres (m) and centimetres (cm), with 1 km = 1000 m and 1 m = 100 cm.
To change a bigger unit to a smaller one, multiply (3 km = 3000 m); to change a smaller unit to a bigger one, divide (400 cm = 4 m).
Example 1: Change 3 km into metres.
3 × 1000 = 3000 m.
Example 2: Change 250 cm into metres and centimetres.
250 cm = 2 m 50 cm.
Quick recap
- 1 km = 1000 m; 1 m = 100 cm.
- Bigger to smaller: multiply. Smaller to bigger: divide.
✓ Quick check
5 km = ___ m?
5 × 1000 = 5000 m.
400 cm = ___ m?
400 ÷ 100 = 4 m.
Weight (kg, g) & Capacity (L, mL)
Weight uses kilograms (kg) and grams (g) with 1 kg = 1000 g. Capacity uses litres (L) and millilitres (mL) with 1 L = 1000 mL.
A mixed measure like 2 kg 500 g equals 2500 g, and 1500 mL equals 1 L 500 mL.
Example 1: Change 2 kg 500 g into grams.
2000 + 500 = 2500 g.
Example 2: Change 3 L into millilitres.
3 × 1000 = 3000 mL.
Quick recap
- 1 kg = 1000 g; 1 L = 1000 mL.
- Combine the parts: 2 kg 500 g = 2500 g.
✓ Quick check
4 kg = ___ g?
4 × 1000 = 4000 g.
1500 mL = ___ ?
1000 mL = 1 L, plus 500 mL, so 1 L 500 mL.
Mixed Units & Word Problems
To add or subtract mixed units, work on each unit separately, regrouping when needed. For 2 m 50 cm + 1 m 30 cm, add metres and centimetres to get 3 m 80 cm.
In word problems, convert to the same unit if necessary, then add or subtract.
Example 1: Add 2 m 50 cm + 1 m 30 cm.
3 m and 80 cm = 3 m 80 cm.
Example 2: Subtract 5 kg − 2 kg 300 g.
5 kg = 4 kg 1000 g; 4 kg 1000 g − 2 kg 300 g = 2 kg 700 g.
Quick recap
- Add/subtract each unit separately, regrouping if needed.
- Convert to the same unit when the problem mixes units.
✓ Quick check
3 m 40 cm + 2 m 20 cm = ?
3 + 2 = 5 m and 40 + 20 = 60 cm, so 5 m 60 cm.
2 L 500 mL − 1 L = ?
2 L 500 mL − 1 L = 1 L 500 mL.
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