Alright, let's work through 6394 times 1943 step by step
6394 × 1943 = 1943 × (6394)
+ 1943 × 4 giving us 7772
+ 1943 × 90 what gives us 174870
+ 1943 × 300 that equals 582900
+ 1943 × 6000 which equals 11658000

= 12423542
