Alright, let's work through 7815 times 1089 step by step
7815 × 1089 = 1089 × (7815)
+ 1089 × 5 which equals 5445
+ 1089 × 10 that results in 10890
+ 1089 × 800 which equals 871200
+ 1089 × 7000 which equals 7623000

= 8510535
