Alright, let's work through 3640 times 5787 step by step
3640 × 5787 = 5787 × (3640)
+ 5787 × 0 what gives us 0
+ 5787 × 40 what gives us 231480
+ 5787 × 600 yielding 3472200
+ 5787 × 3000 resulting in 17361000

= 21064680
