Alright, let's work through 1900 times 6381 step by step
1900 × 6381 = 6381 × (1900)
+ 6381 × 0 resulting in 0
+ 6381 × 00 giving us 0
+ 6381 × 900 yielding 5742900
+ 6381 × 1000 what gives us 6381000

= 12123900
