This 100 Exits walkthrough covers the solution to levels 21 to 30 for the iphone and ipad. In level 21, stack the rings according to their sizes on the left rod then get the key. In level 22, touch the door when the fast yellow car passes. In exit 23, shake device to get painting off the wall then break the wall to reveal the door. In level 27, touch the letters, E X I T then roman numerals for 27 which reads as XXVII. For all other levels not mentioned please refer to the video.