Alright, let's work through 6438 times 4378 step by step
6438 × 4378 = 4378 × (6438)
+ 4378 × 8 producing 35024
+ 4378 × 30 resulting in 131340
+ 4378 × 400 producing 1751200
+ 4378 × 6000 resulting in 26268000

= 28185564
