Alright, let's work through 3879 times 7344 step by step
3879 × 7344 = 7344 × (3879)
+ 7344 × 9 what gives us 66096
+ 7344 × 70 producing 514080
+ 7344 × 800 resulting in 5875200
+ 7344 × 3000 producing 22032000

= 28487376
