Alright, let's work through 3845 times 1878 step by step
3845 × 1878 = 1878 × (3845)
+ 1878 × 5 giving us 9390
+ 1878 × 40 that is equal 75120
+ 1878 × 800 producing 1502400
+ 1878 × 3000 that is equal 5634000

= 7220910
