Alright, let's work through 8643 times 5815 step by step
8643 × 5815 = 5815 × (8643)
+ 5815 × 3 giving us 17445
+ 5815 × 40 that results in 232600
+ 5815 × 600 giving us 3489000
+ 5815 × 8000 yielding 46520000

= 50259045
