Alright, let's work through 9920 times 1643 step by step
9920 × 1643 = 1643 × (9920)
+ 1643 × 0 that results in 0
+ 1643 × 20 yielding 32860
+ 1643 × 900 yielding 1478700
+ 1643 × 9000 which equals 14787000

= 16298560
