No problem, we've got 6397 and 6660 to multiply
6397 × 6660 = 6660 × (6397)
+ 6660 × 7 that equals 46620
+ 6660 × 90 what gives us 599400
+ 6660 × 300 that results in 1998000
+ 6660 × 6000 what gives us 39960000

= 42604020
