Alright, let's work through 6408 times 139 step by step
6408 × 139 = 139 × (6408)
+ 139 × 8 that is equal 1112
+ 139 × 00 that results in 0
+ 139 × 400 giving us 55600
+ 139 × 6000 producing 834000

= 890712
