Converting Metric Units
Convert between common metric units of length, mass and capacity; choose and use decimal representations of metric measurements relevant to the context of a problem.
Read this first
Every step between units is a times or divide by 10, 100 or 1000.
10 mm make 1 cm. 100 cm make 1 m. 1000 m make 1 km.
Words you need
- Convert
- Change from one unit to another.
- Metric
- The unit system based on tens.
- Decimal
- A way of writing part of a whole.
Worked example
e.g. Change 2.4 km into metres.
- Decide which way you are going. Km is bigger than m.
- Going to a smaller unit means the number gets bigger. So multiply.
- 1 km is 1000 m, so multiply by 1000.
- 2.4 x 1000 = 2400 m.
Bigger unit to smaller unit means multiply. The number gets bigger.
Practice
The pictures fade as you go. By the last few you are on your own.
1How many cm in 3 m?with a picture
Answer300 cm.
2How many mm in 5 cm?with a picture
Answer50 mm.
3Change 750 g into kilograms.with a hint
Need a hint?
Going to a bigger unit means divide.
Answer0.75 kg.
4Change 2500 mL into litres.with a hint
Need a hint?
1000 mL make 1 L.
Answer2.5 L.
5Change 0.4 m into centimetres.on your own
Answer40 cm.
6Change 1250 m into kilometres.on your own
Answer1.25 km.
7Add 1.2 m and 30 cm. Give the answer in metres.on your own
Answer1.5 m.
Think about it
1
Why does the number get bigger when the unit gets smaller?
One good answerIt takes more small units to make the same amount.
2
Why convert before adding two measurements?
One good answerYou cannot add metres to centimetres directly.
Common mistakes
Multiplying when you should divide.
Ask first whether the number should get bigger or smaller.
Adding without converting.
Change both to the same unit first.