1millimeter on the map represents 100 meters on the ground. the scale ratio is 1 to

Convert 100 meters to millimeters by the proper conversion factor. Below is the conversion,
             (100 meters) x (1000 millimeters / 1 meter) = 100,000 millimeters
Therefore, the scaling being referred to above is 1 is to 100, 000 or also 1:100,000.