No problem, we've got 6399 and 810 to multiply
6399 × 810 = 810 × (6399)
+ 810 × 9 yielding 7290
+ 810 × 90 that is equal 72900
+ 810 × 300 which equals 243000
+ 810 × 6000 which equals 4860000

= 5183190
