Alright, let's work through 1671 times 1087 step by step
1671 × 1087 = 1087 × (1671)
+ 1087 × 1 yielding 1087
+ 1087 × 70 what gives us 76090
+ 1087 × 600 which equals 652200
+ 1087 × 1000 resulting in 1087000

= 1816377
