sentence: 10 km , 10,000 m , or 1 e+4 m is equal to : 6.2 miles side of square with area 100 km 2 radius of circle with area 314.159 km 2 the classical greeks used letters of the greek alphabet to represent greek numerals : they used a capital letter mu ( μ ) to represent 10000 , whose name in greek is myriad .