No problem, we've got 2631 and 6398 to multiply
2631 × 6398 = 6398 × (2631)
+ 6398 × 1 that is equal 6398
+ 6398 × 30 which equals 191940
+ 6398 × 600 which equals 3838800
+ 6398 × 2000 that is equal 12796000

= 16833138
