Read the paper clue in your room
Current public walkthrough supply agrees on the useful boundary: the Basement keypad number comes from a paper clue inside the puzzle room. Roblox official badge data confirms a key-and-basement escape milestone, but it does not publish a fixed keypad number, puzzle map, or creator-written walkthrough.
That means the safest answer is local to your run: inspect the papers, enter the number you actually see, and check the digits again before testing random codes.