Alright, let's work through 1604 times 9909 step by step
1604 × 9909 = 9909 × (1604)
+ 9909 × 4 that results in 39636
+ 9909 × 00 that is equal 0
+ 9909 × 600 resulting in 5945400
+ 9909 × 1000 that is equal 9909000

= 15894036
