Multiple choice general knowledge math & puzzles If 4 X 3 = 13 and 5 X 3 = 16, then 6 X 3 = 18 20 21 19 Reveal answer Fill a bubble to check yourself D Correct answer Explanation The pattern follows the formula: a X b = a × b + 1. For 4 X 3: 4×3+1=13. For 5 X 3: 5×3+1=16. Therefore, 6 X 3 = 6×3+1 = 19.