Question

How many m are there in 6k m.
How many cm are there in 1.9 m.
How many cm are there in 10 mm.
How many m are there in 6 cm.
How many km are there in 16 m.

Answer 1

6 km = 6000 m
1.9 m = 190 cm
10 mm =1 cm 
6 cm = 0.06 m
16 m = 0.016 km

Answer 2

1 km = 1000m
so 6km = 6×1000 = 6000m

1m = 100cm
1.9m = 1.9×100 = 190cm

1cm = 10mm
so 10mm = 1cm

1m = 100 cm
thus 1cm = 1/100 = 0.01m
so 6cm = 6×0.01 = 0.06m

1km = 1000m
thus 1m = 1/1000 = 0.001km
so 16m = 16×0.001 = 0.016km