No problem, we've got 1684 and 6405 to multiply
1684 × 6405 = 6405 × (1684)
+ 6405 × 4 which equals 25620
+ 6405 × 80 giving us 512400
+ 6405 × 600 that equals 3843000
+ 6405 × 1000 that equals 6405000

= 10786020
