Why does a one-line change to a simulation answer birthday questions that the closed-form formula cannot?
Short drills on what this video just taught. Write the code, run the checks, and reveal the answer only if you are stuck.
There are days possible birthdays. By the pigeonhole principle, find the smallest group size that guarantees at least two people share a birthday, and the smallest that guarantees at least three do. Assign them to two and three.