Alright, let's work through 1635 times 8286 step by step
1635 × 8286 = 8286 × (1635)
+ 8286 × 5 which equals 41430
+ 8286 × 30 yielding 248580
+ 8286 × 600 resulting in 4971600
+ 8286 × 1000 which equals 8286000

= 13547610
