Alright, let's work through 6621 times 3131 step by step
6621 × 3131 = 3131 × (6621)
+ 3131 × 1 what gives us 3131
+ 3131 × 20 what gives us 62620
+ 3131 × 600 yielding 1878600
+ 3131 × 6000 yielding 18786000

= 20730351
