No problem, we've got 3423 and 6240 to multiply
3423 × 6240 = 6240 × (3423)
+ 6240 × 3 that results in 18720
+ 6240 × 20 that equals 124800
+ 6240 × 400 yielding 2496000
+ 6240 × 3000 that results in 18720000

= 21359520
