No problem, we've got 3977 and 4020 to multiply
3977 × 4020 = 4020 × (3977)
+ 4020 × 7 that results in 28140
+ 4020 × 70 producing 281400
+ 4020 × 900 giving us 3618000
+ 4020 × 3000 yielding 12060000

= 15987540
