Alright, let's work through 8643 times 7957 step by step
8643 × 7957 = 7957 × (8643)
+ 7957 × 3 resulting in 23871
+ 7957 × 40 resulting in 318280
+ 7957 × 600 which equals 4774200
+ 7957 × 8000 resulting in 63656000

= 68772351
