Before revision: The ellipsoid WGS-84, widely used for mapping and satellite navigation has close to 1/300 (more precisely, 1/298.257223563, by definition), corresponding to a difference of the major and minor semi-axes of approximately (more precisely, 21.3846858 km).
After revision: The ellipsoid WGS-84, widely used for mapping and satellite navigation has close to 1/300 (more precisely, 1/298.257223563, by definition), corresponding to a difference of the major and minor semi-axes of approximately (more precisely, 21.3846857548205 km).