No problem, we've got 6407 and 6400 to multiply
6407 × 6400 = 6400 × (6407)
+ 6400 × 7 giving us 44800
+ 6400 × 00 producing 0
+ 6400 × 400 producing 2560000
+ 6400 × 6000 producing 38400000

= 41004800
