Alright, let's work through 1641 times 7856 step by step
1641 × 7856 = 7856 × (1641)
+ 7856 × 1 what gives us 7856
+ 7856 × 40 producing 314240
+ 7856 × 600 that is equal 4713600
+ 7856 × 1000 that is equal 7856000

= 12891696
