Alright, let's work through 4099 times 5108 step by step
4099 × 5108 = 5108 × (4099)
+ 5108 × 9 producing 45972
+ 5108 × 90 yielding 459720
+ 5108 × 000 what gives us 0
+ 5108 × 4000 producing 20432000

= 20937692
