Alright, let's work through 3602 times 5725 step by step
3602 × 5725 = 5725 × (3602)
+ 5725 × 2 producing 11450
+ 5725 × 00 that is equal 0
+ 5725 × 600 giving us 3435000
+ 5725 × 3000 which equals 17175000

= 20621450
