Alright, let's work through 6391 times 6129 step by step
6391 × 6129 = 6129 × (6391)
+ 6129 × 1 giving us 6129
+ 6129 × 90 that results in 551610
+ 6129 × 300 that equals 1838700
+ 6129 × 6000 yielding 36774000

= 39170439
