Converting linear units into metric are as follow.
10 millimetres (mm) 
1 centimetre (cm) 
10 centimetres (cm) 
1 decimetre (dm) 
10 decimtres (dm) 
1 metre (m) 
10 metres (m) 
1 decametre (Dm) 
10 decametres (Dm) 
1 hectometre (hm) 
10 hectometres (hm) 
1 kilometre (km) 
NB: The following sentence is useful for remembering the prefixes of linear units in the metric system:
"King Henry died of a miserable disease called measles."
Converting linear units in the metric system
King 
Henry 
died of a 
Miserable 
Disease 
Called 
Measles 
kilometre 
hectometre 
decametre 
metre 
decimetre 
centimetre 
millimetre 
km 
hm 
Dm 
m 
dm 
cm 
mm 
Converting from larger units to smaller units. For example: kilometre to metres, you multiply by 10 for every unit.
Example:
Convert 1,452km to m, you are changing to a smaller unit and so you multiply by ten for every unit.
1,452km x 10 x 10 x 10 = 1,452 x 1 000m
= 1 452m
Distance
km 
hm 
Dm 
m 
dm 
cm 
mm 
1, 
4 
5 
2 



1 
4 
5 
2, 
0 


Converting from smaller units to larger units. For example:millimetres to metres, you divide by 10 every unit.
km 
hm 
Dm 
m 
dm 
cm 
mm 




1 
2 
5, 



0, 
1 
2 
5 
So when converting 125mm to m you are changing to a larger unit so you divide by ten for every unit. Remember that 125mm can be written as 125,0mm? In the table above you will see the comma after the 5 in the mm column. To divide by10 you move the comma one place to the left. But in this question we move the comma 3 places to the left because to convert to metres you divide by 10 three times.
125mm ÷ 10 ÷ 10 ÷ = 125 ÷ 1000m
=0,125m
1 000 millimetres(ml) = 1 litre
In real life we usually only need to convert between millimetres, ventimetres, metres and kilometres.
10mm = 1cm
100cm = 1cm
Converting units of mass in the metric system
Units we use when working with mass are gram, kilograms and tonne. In the metric a tonne (t) sometime called a metric ton is a unit of mass equal to 1 000kg.
Conversion
1 000g 
1kg 
1 000kg 
1t 
Learner can Watch the following video, of conversion of measurement.
https://www.youtube.com/watch?v=FFTDCfs4oHc