Just using more doors (both for the total, and the number he opens) is probably enough to make it clear. Like 1000 doors. If I choose one at random I am pretty

Just using more doors (both for the total, and the number he opens) is probably enough to make it clear. Like 1000 doors. If I choose one at random I am pretty unlikely to be right on that first choice. But then he opens 998 of the unchosen doors, knowing he won't open the door with the car, I would think oh if it was originally in any of the 999 unchosen doors it is in the one he didn't open.