No problem, we've got 1581 and 7719 to multiply
1581 × 7719 = 7719 × (1581)
+ 7719 × 1 what gives us 7719
+ 7719 × 80 which equals 617520
+ 7719 × 500 that equals 3859500
+ 7719 × 1000 what gives us 7719000

= 12203739
