Alright, let's work through 8424 times 9210 step by step
8424 × 9210 = 9210 × (8424)
+ 9210 × 4 producing 36840
+ 9210 × 20 which equals 184200
+ 9210 × 400 which equals 3684000
+ 9210 × 8000 that results in 73680000

= 77585040
