No problem, we've got 2439 and 3420 to multiply
2439 × 3420 = 3420 × (2439)
+ 3420 × 9 that is equal 30780
+ 3420 × 30 that results in 102600
+ 3420 × 400 that equals 1368000
+ 3420 × 2000 resulting in 6840000

= 8341380
