Alright, let's work through 1591 times 5131 step by step
1591 × 5131 = 5131 × (1591)
+ 5131 × 1 yielding 5131
+ 5131 × 90 that equals 461790
+ 5131 × 500 that is equal 2565500
+ 5131 × 1000 which equals 5131000

= 8163421
