Matthew Gilliard's post explores the Doomsday algorithm, a method devised by John Horton Conway to determine the day of the week for any given date, offering a practical way to impress others with quick calendar calculations. The article explains how to find the "Doomsday" for any year and provides memorable anchor dates to simplify the process. To aid in mastering this algorithm, the post guides readers through building an SMS chatbot using Twilio Studio and Twilio Functions that tests the user's Doomsday calculations by sending random dates and verifying responses. This interactive approach not only enhances one's proficiency in the algorithm but also showcases the capabilities of Twilio's serverless platform in creating conversational workflows.