Problem #47 MEDIUM
The Number on My Forehead
Microsoft Adobe Logic Game Theory
Problem Statement
Three brilliant mathematicians — Priya, Rahul, and Sneha — each have a positive integer written on their forehead. They can see the other two numbers but not their own. They are told that one of the three numbers equals the sum of the other two. They take turns (P, R, S, P, R, S...) and each says either 'I know my number' or 'I do not know.' Priya and Rahul both say 'I do not know.' Sneha then says 'I know my number.' What is Sneha's number, given that the numbers on Priya and Rahul's foreheads are 20 and 30?
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