Alright, let's work through 2916 times 4245 step by step
2916 × 4245 = 4245 × (2916)
+ 4245 × 6 yielding 25470
+ 4245 × 10 that equals 42450
+ 4245 × 900 producing 3820500
+ 4245 × 2000 yielding 8490000

= 12378420
