No problem, we've got 1643 and 3881 to multiply
1643 × 3881 = 3881 × (1643)
+ 3881 × 3 what gives us 11643
+ 3881 × 40 which equals 155240
+ 3881 × 600 giving us 2328600
+ 3881 × 1000 resulting in 3881000

= 6376483
