Alright, let's work through 1638 times 9935 step by step
1638 × 9935 = 9935 × (1638)
+ 9935 × 8 that equals 79480
+ 9935 × 30 which equals 298050
+ 9935 × 600 that equals 5961000
+ 9935 × 1000 yielding 9935000

= 16273530
