Alright, let's work through 9891 times 9105 step by step
9891 × 9105 = 9105 × (9891)
+ 9105 × 1 what gives us 9105
+ 9105 × 90 yielding 819450
+ 9105 × 800 what gives us 7284000
+ 9105 × 9000 producing 81945000

= 90057555
