Alright, let's work through 6123 times 2545 step by step
6123 × 2545 = 2545 × (6123)
+ 2545 × 3 producing 7635
+ 2545 × 20 yielding 50900
+ 2545 × 100 giving us 254500
+ 2545 × 6000 what gives us 15270000

= 15583035
