Alright, let's work through 6640 times 7819 step by step
6640 × 7819 = 7819 × (6640)
+ 7819 × 0 which equals 0
+ 7819 × 40 resulting in 312760
+ 7819 × 600 that is equal 4691400
+ 7819 × 6000 that results in 46914000

= 51918160
