Alright, let's work through 8258 times 5121 step by step
8258 × 5121 = 5121 × (8258)
+ 5121 × 8 resulting in 40968
+ 5121 × 50 that equals 256050
+ 5121 × 200 that results in 1024200
+ 5121 × 8000 resulting in 40968000

= 42289218
