Alright, let's work through 4139 times 2105 step by step
4139 × 2105 = 2105 × (4139)
+ 2105 × 9 that results in 18945
+ 2105 × 30 producing 63150
+ 2105 × 100 producing 210500
+ 2105 × 4000 giving us 8420000

= 8712595
