Alright, let's work through 3891 times 4778 step by step
3891 × 4778 = 4778 × (3891)
+ 4778 × 1 that results in 4778
+ 4778 × 90 that is equal 430020
+ 4778 × 800 that equals 3822400
+ 4778 × 3000 that equals 14334000

= 18591198
