Alright, let's work through 3991 times 419 step by step
3991 × 419 = 419 × (3991)
+ 419 × 1 that is equal 419
+ 419 × 90 that results in 37710
+ 419 × 900 giving us 377100
+ 419 × 3000 that results in 1257000

= 1672229
