There are 3 doors. Behind 1 one of them is a brand new car.
You can pick 1 door.
You randomly choose door 1. The quizmaster then opens door number 3 to show you the car is not behind that door.
He then asks you if you still will go for door 1 or if you want to switch to door 2.
Always switch to the other door because your chances will go from 1 in 3 to 2 in 3 instantly
