No problem, we've got 2639 and 7997 to multiply
2639 × 7997 = 7997 × (2639)
+ 7997 × 9 that results in 71973
+ 7997 × 30 yielding 239910
+ 7997 × 600 what gives us 4798200
+ 7997 × 2000 giving us 15994000

= 21104083
