Alright, let's work through 4082 times 5100 step by step
4082 × 5100 = 5100 × (4082)
+ 5100 × 2 that results in 10200
+ 5100 × 80 what gives us 408000
+ 5100 × 000 producing 0
+ 5100 × 4000 that equals 20400000

= 20818200
