Alright, let's work through 6640 times 1865 step by step
6640 × 1865 = 1865 × (6640)
+ 1865 × 0 giving us 0
+ 1865 × 40 that results in 74600
+ 1865 × 600 which equals 1119000
+ 1865 × 6000 which equals 11190000

= 12383600
