Alright, let's work through 4086 times 7780 step by step
4086 × 7780 = 7780 × (4086)
+ 7780 × 6 that results in 46680
+ 7780 × 80 what gives us 622400
+ 7780 × 000 which equals 0
+ 7780 × 4000 yielding 31120000

= 31789080
