sentence: distances shorter than 10 metres conversions 10 metres ( very rarely termed a decametre which is abbreviated as dam ) is equal to : 10 metre 100 decimetre 1,000 centimetre 10,000 millimetre 32.8 feet side of square with area 100 m² human-defined scales and structures 10 metres wavelength of the highest shortwave radio frequency , 30 m hz 23 metres height of the obelisk of the place de la concorde , paris , france .