This would depend on the scale of the map. If the map scale is 1:100, then 1 cm on the map would represent 100 cm (or 1 m) on the ground. Therefore, to find out how many centimetres on the map will show 50000 centimetres on the ground, you would divide 50000 by 100, which equals 500. So, 500 centimetres on the map would represent 50000 centimetres on the ground if the map scale is 1:100.
