Alright, let's work through 3899 times 5158 step by step
3899 × 5158 = 5158 × (3899)
+ 5158 × 9 that is equal 46422
+ 5158 × 90 that results in 464220
+ 5158 × 800 that equals 4126400
+ 5158 × 3000 that is equal 15474000

= 20111042
