 Public Announcement Logic (PAL) is the modal logic study of knowledge, belief, and public communication. PAL (pronounced “pal”) is used to reason about knowledge and belief and the changes brought about in knowledge and belief as per the occurrence of completely trustworthy, truthful announcements. PAL’s most common motivational examples include the Muddy Children Puzzle and the Sum and Product Puzzle (see, e.g., Plaza 1989, 2007). The Cheryl’s Birthday problem, which became a sensation on the Internet in April 2015, can also be addressed using PAL. Here we present a version of the Cheryl’s Birthday problem due to Chang (2015, 15 April) and a three-child version of the Muddy Children Puzzle (Fagin et al. 1995). Instead of presenting the traditional Sum and Product Puzzle (see Plaza (1989, 2007) for details), we present our own simplification that we call the Sum and Least Common Multiple Problem. 