Alright, let's work through 1637 times 1643 step by step
1637 × 1643 = 1643 × (1637)
+ 1643 × 7 what gives us 11501
+ 1643 × 30 giving us 49290
+ 1643 × 600 that is equal 985800
+ 1643 × 1000 what gives us 1643000

= 2689591
