Recall that the most common ** metric units of length** used are the kilometre (km), the
metre (m), the centimetre (cm) and the millimetre (mm). These units of
length are related as follows:
Note that we would measure the:
- thickness of the rubber sheet for a table tennis bat in millimetres.
- width of a television screen in centimetres.
- width of a road in metres.
- distance between two airports in kilometres.
Various instruments are used to measure length. For example:
**rulers** and **tape measures **are marked in millimetres or
centimetres to measure shorter lengths accurately.
- a
**trundle wheel **is used to measure length to the nearest metre.
Note that a counter may be attached to the trundle wheel to count
metres.
- a car's
**odometer **often measures distance in tenths of a
kilometre.
### Converting Metric Units
We know that:
This suggests that:
- To convert length from a larger unit into a smaller unit, multiply by the
relevant power of 10.
- To convert length from a smaller unit into a larger unit, divide by the
relevant power of 10.
You should be able to work confidently with metric units to solve
problems in daily life.
Example 1
Convert the following measurements to the units indicated:
a. 7 cm to mm
b. 8 m to cm
c. 9 km to m
##### Solution:
Example 2
Convert the following measurements to the units indicated:
a. 6 m to mm
b. 4 km to cm
c. 3 km to mm
##### Solution:
Example 3
Convert the following measurements to the units indicated:
a. 62.8 cm to mm
b. 48.7 m to cm
c. 8.26 m to mm
d. 4.75 km to mm
##### Solution:
Example 4
Convert the following measurements to the units indicated:
a. 975 m to km
b. 650 cm to m
c. 8000 mm to m
d. 950 000 cm to km
##### Solution:
Key Terms
length, metric units of length, kilometre, metre, centimetre, millimetre, ruler, tape measure, trundle
wheel, odometer |