No problem, we've got 1792 and 780 to multiply
1792 × 780 = 780 × (1792)
+ 780 × 2 that is equal 1560
+ 780 × 90 what gives us 70200
+ 780 × 700 what gives us 546000
+ 780 × 1000 producing 780000

= 1397760
