Alright, let's work through 9641 times 643 step by step
9641 × 643 = 643 × (9641)
+ 643 × 1 what gives us 643
+ 643 × 40 resulting in 25720
+ 643 × 600 that results in 385800
+ 643 × 9000 that results in 5787000

= 6199163
