Alright, let's work through 8644 times 9985 step by step
8644 × 9985 = 9985 × (8644)
+ 9985 × 4 that equals 39940
+ 9985 × 40 giving us 399400
+ 9985 × 600 which equals 5991000
+ 9985 × 8000 what gives us 79880000

= 86310340
