Alright, let's work through 3331 times 6404 step by step
3331 × 6404 = 6404 × (3331)
+ 6404 × 1 yielding 6404
+ 6404 × 30 what gives us 192120
+ 6404 × 300 giving us 1921200
+ 6404 × 3000 producing 19212000

= 21331724
