Alright, let's work through 8489 times 9903 step by step
8489 × 9903 = 9903 × (8489)
+ 9903 × 9 resulting in 89127
+ 9903 × 80 yielding 792240
+ 9903 × 400 that is equal 3961200
+ 9903 × 8000 what gives us 79224000

= 84066567
