Found this on the bbc website
F1 WORLD CHAMPIONSHIP MATHS
Button will win the title in Brazil if...
He finishes third or better
OR Vettel finishes lower than second and Barrichello finishes lower than fourth
OR he outscores Barrichello by four points
F1 WORLD CHAMPIONSHIP MATHS
Button will win the title in Brazil if...
He finishes third or better
OR Vettel finishes lower than second and Barrichello finishes lower than fourth
OR he outscores Barrichello by four points