Alright, let's work through 1665 times 7700 step by step
1665 × 7700 = 7700 × (1665)
+ 7700 × 5 yielding 38500
+ 7700 × 60 giving us 462000
+ 7700 × 600 resulting in 4620000
+ 7700 × 1000 which equals 7700000

= 12820500
