How many decimeters are in one kilometer?

1 km = 1000 m

1 dm = 0.1 m

So, 10,000 dm = 1 km.

Here's a calculation showing units:

(1000 m/km) / (0.1 m/dm) = (1000 m/km) * (1 dm / 0.1 m) = 1000 dm / 0.1 km = 10,000 dm/km.