Alright, let's work through 6458 times 2099 step by step
6458 × 2099 = 2099 × (6458)
+ 2099 × 8 which equals 16792
+ 2099 × 50 that equals 104950
+ 2099 × 400 producing 839600
+ 2099 × 6000 which equals 12594000

= 13555342
