Alright, let's work through 3644 times 6407 step by step
3644 × 6407 = 6407 × (3644)
+ 6407 × 4 giving us 25628
+ 6407 × 40 what gives us 256280
+ 6407 × 600 resulting in 3844200
+ 6407 × 3000 what gives us 19221000

= 23347108
