The commercial pilot was taking a practical test and was demonstrating a simulated short field landing over a simulated 50 foot obstacle. The commercial pilot reported that he had planned to touch down on or within 100 feet past the “numbers” painted on the runway. The painted numbers were 60 feet long and about 18 feet from the approach end of the runway. The airplane touched down short of the intended landing spot and the right main landing gear struck the edge of the runway surface and caused a loud “bang” heard by both the commercial pilot and by the pilot examiner. A postflight examination showed substantial damage to the right wing where three wing ribs separated from the spar web and partially penetrated through the upper skin. The commercial pilot added that the accident could have been avoided if he had picked a touchdown spot further away from the end of the runway.