Alright, let's work through 3621 times 1015 step by step
3621 × 1015 = 1015 × (3621)
+ 1015 × 1 which equals 1015
+ 1015 × 20 producing 20300
+ 1015 × 600 that is equal 609000
+ 1015 × 3000 which equals 3045000

= 3675315
