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ID60-Jokers Can Not be Used as a Single Tiles or in a Pair
Question: Can I use a Joker as a single tile or in a pair?
Answer: Under no circumstance can a Joker be used in place of a single tile or a pair. If you were to call and exposure a single grouping or a pair with a joker, your hand would be declared dead.
Source: Mah Jongg Made Easy (2020 page 23, #10, page 30 para. 6)