Alright, let's work through 5991 times 613 step by step
5991 × 613 = 613 × (5991)
+ 613 × 1 yielding 613
+ 613 × 90 that results in 55170
+ 613 × 900 that equals 551700
+ 613 × 5000 resulting in 3065000

= 3672483
