Alright, let's work through 6289 times 1639 step by step
6289 × 1639 = 1639 × (6289)
+ 1639 × 9 that is equal 14751
+ 1639 × 80 resulting in 131120
+ 1639 × 200 what gives us 327800
+ 1639 × 6000 yielding 9834000

= 10307671
