When we have the prefix (before a word) kilo it means 1000
1 kilogram = 1000 grams
1 kilometre = 1000 metres
When we have the prefix (before a word) milli it means 1⁄1000
1000 millimetres = 1 metre
1000 millilitres = 1 litre
When we have the prefix centi it means 1⁄100
100 centimetres = 1 metre
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A measurement has a number and a unit, such as 30 cm30 \, \text{cm}30cm. A conversion changes the unit without changing the actual length, mass, or capacity, so the amount stays the same.
Useful facts are 1 km=1000 m1 \, \text{km} = 1000 \, \text{m}1km=1000m, 1 m=100 cm1 \, \text{m} = 100 \, \text{cm}1m=100cm, 1 cm=10 mm1 \, \text{cm} = 10 \, \text{mm}1cm=10mm, 1 kg=1000 g1 \, \text{kg} = 1000 \, \text{g}1kg=1000g, and 1 L=1000 ml1 \, \text{L} = 1000 \, \text{ml}1L=1000ml. Big unit to small unit means multiply, and small unit to big unit means divide.
Do a quick size check before you calculate. If the target unit is smaller, your answer should be a bigger number, and if the target unit is bigger, your answer should be a smaller number.
Question 1
1 markChange 2580 grams to kilograms.
In 30 cm, what is the unit?
Revision notes for Edexcel GCSE Maths Metric Conversions. Open the guide for explanations and worked examples. Written against the Edexcel GCSE Maths (1MA1) specification, so the content matches what's examinable rather than general Maths background.
1 of 3
A piece of string is 4 m long. What is this length in centimetres?
1 of 3
Convert 3.5 metres into centimetres.
