FOUR - DOOR
If you are still having trouble remembering 4 = door, try one of the following:
1. Use paper to make a LARGE number 4 on a door. Every time you look at the door, you will think 4 = door.
2. Play "knock, knock" with one of your friend.
Say, "knock, knock." They will respond, "Who's there?" Your response is, "Four." They will say, "Four who?" You say, "Four Door." (They will probably respond with a puzzled look, but you are on your way to remembering 4 = door)