8420 ÷ 5 = 1684 R0
Alright, let's work through the division of 8420 by 5 step by step.

Step 1:
5 goes into 8 1 times with a remainder of 3.
Write down 1 as next digit of of the result. 
Result so far: 1
Subtract 5 from 8 to get 3.
Bring next digit (4) of the dividend behind the 3 and repeat the process: 34 / 5

Step 2:
5 goes into 34 6 times with a remainder of 4.
Write down 6 as next digit of of the result. 
Result so far: 16
Subtract 30 from 34 to get 4.
Bring next digit (2) of the dividend behind the 4 and repeat the process: 42 / 5

Step 3:
5 goes into 42 8 times with a remainder of 2.
Write down 8 as next digit of of the result. 
Result so far: 168
Subtract 40 from 42 to get 2.
Bring next digit (0) of the dividend behind the 2 and repeat the process: 20 / 5

Step 4:
5 goes into 20 4 times with a remainder of 0.
Write down 4 as next digit of of the result. 
Result so far: 1684
Subtract 20 from 20 to get 0.

The final result is 1684 with a remainder of 0.