Multiple choice general knowledge math & puzzles Look at this series: 0.15, 0.3, ____, 1.2, 2.4, ... What number should fill the blank? 4.8 0.006 0.6 0.9 Reveal answer Fill a bubble to check yourself C Correct answer Explanation This is a doubling sequence: each number is multiplied by 2. Starting with 0.15: 0.15 × 2 = 0.3, 0.3 × 2 = 0.6, 0.6 × 2 = 1.2, 1.2 × 2 = 2.4. The missing number is 0.6. Option C is correct.