Alright, let's work through 3451 times 5418 step by step
3451 × 5418 = 5418 × (3451)
+ 5418 × 1 that results in 5418
+ 5418 × 50 yielding 270900
+ 5418 × 400 that results in 2167200
+ 5418 × 3000 giving us 16254000

= 18697518
