Alright, let's work through 1089 times 7860 step by step
1089 × 7860 = 7860 × (1089)
+ 7860 × 9 what gives us 70740
+ 7860 × 80 producing 628800
+ 7860 × 000 giving us 0
+ 7860 × 1000 which equals 7860000

= 8559540
