Alright, let's work through 1280 times 3992 step by step
1280 × 3992 = 3992 × (1280)
+ 3992 × 0 that is equal 0
+ 3992 × 80 giving us 319360
+ 3992 × 200 giving us 798400
+ 3992 × 1000 that is equal 3992000

= 5109760
