Puzzles and logic › Processes, invariants and strategy › Board operations and invariants
Reachable values on a blackboard
High school · ●●●●○ 100 pts
Svitlana writes the number 147 on a blackboard. Then, at any point, if the number on the blackboard is , she can perform one of the following three operations: if is even, she can replace with ; if is odd, she can replace with ; and if , she can replace with . Compute the number of possible values that Svitlana can obtain by doing zero or more operations.