Alright, let's work through 2551 times 6640 step by step
2551 × 6640 = 6640 × (2551)
+ 6640 × 1 giving us 6640
+ 6640 × 50 which equals 332000
+ 6640 × 500 what gives us 3320000
+ 6640 × 2000 that equals 13280000

= 16938640
