Alright, let's work through 3158 times 6621 step by step
3158 × 6621 = 6621 × (3158)
+ 6621 × 8 that is equal 52968
+ 6621 × 50 yielding 331050
+ 6621 × 100 that equals 662100
+ 6621 × 3000 producing 19863000

= 20909118
