Alright, let's work through 3187 times 6391 step by step
3187 × 6391 = 6391 × (3187)
+ 6391 × 7 yielding 44737
+ 6391 × 80 what gives us 511280
+ 6391 × 100 which equals 639100
+ 6391 × 3000 that results in 19173000

= 20368117
