Alright, let's work through 8155 times 1580 step by step
8155 × 1580 = 1580 × (8155)
+ 1580 × 5 that equals 7900
+ 1580 × 50 what gives us 79000
+ 1580 × 100 resulting in 158000
+ 1580 × 8000 giving us 12640000

= 12884900
