Unit Conversions

The CSSE maths paper often includes questions that involve converting between different units of length, mass, capacity, and time. You must know the key conversion facts and be confident applying them, especially in multi-step word problems.

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Length Conversions

Conversion	Fact
1 kilometre (km)	= 1,000 metres (m)
1 metre (m)	= 100 centimetres (cm)
1 centimetre (cm)	= 10 millimetres (mm)
1 metre (m)	= 1,000 millimetres (mm)

Worked Example

Convert 3.45 km to metres.

3.45 × 1,000 = 3,450 m

Worked Example

Convert 2,750 mm to metres.

2,750 ÷ 1,000 = 2.75 m

Worked Example

A piece of rope is 4.2 m long. A craftsman cuts off 85 cm. How much rope is left in centimetres?

• 4.2 m = 420 cm
• 420 - 85 = 335 cm

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Mass (Weight) Conversions

Conversion	Fact
1 kilogram (kg)	= 1,000 grams (g)
1 tonne (t)	= 1,000 kilograms (kg)

Worked Example

Convert 4.6 kg to grams.

4.6 × 1,000 = 4,600 g