Alright, let's work through 3131 times 645 step by step
3131 × 645 = 645 × (3131)
+ 645 × 1 that results in 645
+ 645 × 30 producing 19350
+ 645 × 100 that is equal 64500
+ 645 × 3000 resulting in 1935000

= 2019495
