Alright, let's work through 6443 times 1688 step by step
6443 × 1688 = 1688 × (6443)
+ 1688 × 3 giving us 5064
+ 1688 × 40 that is equal 67520
+ 1688 × 400 which equals 675200
+ 1688 × 6000 yielding 10128000

= 10875784
