Alright, let's work through 3603 times 5613 step by step
3603 × 5613 = 5613 × (3603)
+ 5613 × 3 giving us 16839
+ 5613 × 00 producing 0
+ 5613 × 600 giving us 3367800
+ 5613 × 3000 giving us 16839000

= 20223639
