We're going to solve 3871 multiplied by 1810
3871 × 1810 = 1810 × (3871)
+ 1810 × 1 that is equal 1810
+ 1810 × 70 what gives us 126700
+ 1810 × 800 what gives us 1448000
+ 1810 × 3000 resulting in 5430000

= 7006510
