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ID37-What do you Pay the Winner and who Determines the Value?
Question: When we are playing for money or points, who is responsible for tallying a player’s score? How do I know what I have to pay the winner?
Answer: The winning player (winner) is responsible for announcing the value of their hand. In the situation where the winning player forgets to include the value for a jokerless hand and another player points it out, the winning player is paid what they initially declared.
Source: Mah Jongg Made Easy (2020 page 30 para. 11)