Multiple choice general knowledge math & puzzles What decimal of an hour is a second ? 0.027 0.00256 0.00027 none Reveal answer Fill a bubble to check yourself C Correct answer Explanation One second equals 1/3600 of an hour (60 seconds × 60 minutes = 3600 seconds per hour). Therefore, 1 ÷ 3600 = 0.000277... The correct answer 0.00027 is a reasonable approximation to two significant decimal places.