Alright, let's work through 2640 times 5412 step by step
2640 × 5412 = 5412 × (2640)
+ 5412 × 0 resulting in 0
+ 5412 × 40 that equals 216480
+ 5412 × 600 yielding 3247200
+ 5412 × 2000 that equals 10824000

= 14287680
