Alright, let's work through 8121 times 2545 step by step
8121 × 2545 = 2545 × (8121)
+ 2545 × 1 giving us 2545
+ 2545 × 20 yielding 50900
+ 2545 × 100 that equals 254500
+ 2545 × 8000 producing 20360000

= 20667945
