1m=100cm

1cm=10mm

1mm=0.1cm

1cm=0.01m

1m=0.001km

1) The abbreviation “cm” stands for centimetre; there are 100 centimetres in a metre, just as there are 100 years in a century (*cent*ury). “Kilo” means 1000; there are 1000 metres in one kilometre.

Thus, 3.9 cm = 3.9/100 metres, = .039 m. Since there are 1000 metres in a kilometre, you need to divide this number by 1000 to get the final answer: .039 m/1000 = .000039 kilometres (km).

2) There are 1000 milimetres (mm) in a metre. There are 100 centimetres (cm) in a metre. Therefore, a 1 mm = 1/10 cm. Thus, 0.4 mm/10 = .004 cm.

3) There are 1000 metres in a kilometre (km). Therefore, 90m/1000 = .09 km.

4) As mentioned above, 1000 mm = 1 m. Therefore,

2500/1000 = 2.5 m.

If you put “3.9 cm” over the cm spot, you need to move 5 spots to the left to get to km — move your decimal five times to the left. 3.9 cm = 0.000039 km

(You are actually dividing by 10s to get there; when you move right, you are multiplying by tens.)

This works for liters and for grams as well.

kl hl dl liter dkl cl ml

and

kg hg dg grams dkg cg mg