Alright, let's work through 6378 times 2405 step by step
6378 × 2405 = 2405 × (6378)
+ 2405 × 8 giving us 19240
+ 2405 × 70 resulting in 168350
+ 2405 × 300 that results in 721500
+ 2405 × 6000 resulting in 14430000

= 15339090
