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Numbers, units and arithmetic
Numbers, units and arithmetic

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Activity 17

A person’s height is given as 1.65 m. What is this in centimetres?


1.65 m is 165 cm (multiply by 100).

Activity 18

Try the following conversions:

  • (a) Express 675 mm in centimetres.

  • (b) Express 45.2 km in metres.

  • (c) Express 3.5 kg in grams.

  • (d) Express 167.2 mm in metres.


  • (a) To convert millimetres to centimetres, divide by 10. So 675 mm is 67.5 cm.

  • (b) 45.2 km is 45 200 m (multiply by 1000).

  • (c) 3.5 kg is 3500 g (multiply by 1000).

  • (d) 167.2 mm is 0.1672 m (divide by 1000).

Activity 19

A kitchen unit is 1200 mm long, 600 mm high and 350 mm deep. Write these measurements in metres.


To convert millimetres to metres, divide by a thousand, i.e. move the numbers three places to the right in the place value table. In terms of metres, the kitchen unit is then 1.2 m long, 0.6 m high and 0.35 m deep.

We will now provide more detail on converting units using interactive activities.