No problem, we've got 6399 and 685 to multiply
6399 × 685 = 685 × (6399)
+ 685 × 9 that is equal 6165
+ 685 × 90 giving us 61650
+ 685 × 300 what gives us 205500
+ 685 × 6000 resulting in 4110000

= 4383315
