Alright, let's work through 3421 times 8310 step by step
3421 × 8310 = 8310 × (3421)
+ 8310 × 1 what gives us 8310
+ 8310 × 20 that is equal 166200
+ 8310 × 400 that results in 3324000
+ 8310 × 3000 that equals 24930000

= 28428510
