Multiple choice general knowledge math & puzzles If one-third of one-fourth of a number is 15, then three-tenth of that number is: 35 54 36 45 Reveal answer Fill a bubble to check yourself B Correct answer Explanation Let the number be x. (1/3) * (1/4) * x = 15, so x/12 = 15, which means x = 180. Three-tenth of 180 is (3/10) * 180 = 54.