Alright, let's work through 3391 times 4087 step by step
3391 × 4087 = 4087 × (3391)
+ 4087 × 1 which equals 4087
+ 4087 × 90 resulting in 367830
+ 4087 × 300 producing 1226100
+ 4087 × 3000 that equals 12261000

= 13859017
