Alright, let's work through 8121 times 8720 step by step
8121 × 8720 = 8720 × (8121)
+ 8720 × 1 what gives us 8720
+ 8720 × 20 that equals 174400
+ 8720 × 100 producing 872000
+ 8720 × 8000 that results in 69760000

= 70815120
