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 36 45 54 Reveal answer Fill a bubble to check yourself D Correct answer Explanation Let the number be x. Then (1/3)×(1/4)×x = 15, so x/12 = 15, giving x = 180. Three-tenth of this number is (3/10)×180 = 54. Option D is correct. Option A (35) and B (36) are incorrect, and C (45) would be one-fourth of 180, not three-tenths.