Alright, let's work through 3991 times 617 step by step
3991 × 617 = 617 × (3991)
+ 617 × 1 that results in 617
+ 617 × 90 what gives us 55530
+ 617 × 900 yielding 555300
+ 617 × 3000 what gives us 1851000

= 2462447
