Multiple choice general knowledge math & puzzles 7 months of the year have 31 days; how many have 28? 3 1 9 12 Reveal answer Fill a bubble to check yourself D Correct answer Explanation Every month of the year has at least 28 days. While February is the only month with exactly 28 days (usually), all 12 months contain a 28th day. This is a common lateral thinking puzzle.