Alright, let's work through 3805 times 638 step by step
3805 × 638 = 638 × (3805)
+ 638 × 5 what gives us 3190
+ 638 × 00 what gives us 0
+ 638 × 800 what gives us 510400
+ 638 × 3000 giving us 1914000

= 2427590
