Alright, let's work through 1409 times 8413 step by step
1409 × 8413 = 8413 × (1409)
+ 8413 × 9 what gives us 75717
+ 8413 × 00 resulting in 0
+ 8413 × 400 resulting in 3365200
+ 8413 × 1000 what gives us 8413000

= 11853917
