No problem, we've got 1392 and 4390 to multiply
1392 × 4390 = 4390 × (1392)
+ 4390 × 2 what gives us 8780
+ 4390 × 90 yielding 395100
+ 4390 × 300 that equals 1317000
+ 4390 × 1000 what gives us 4390000

= 6110880
