3420 ÷ 8 = 427 R4
We're going to perform division on 3420 with 8 as the divisor.

Step 1:
8 goes into 3 0 times with a remainder of 3.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 3 to get 3.
Bring next digit (4) of the dividend behind the 3 and repeat the process: 34 / 8

Step 2:
8 goes into 34 4 times with a remainder of 2.
Write down 4 as next digit of of the result. 
Result so far: 4
Subtract 32 from 34 to get 2.
Bring next digit (2) of the dividend behind the 2 and repeat the process: 22 / 8

Step 3:
8 goes into 22 2 times with a remainder of 6.
Write down 2 as next digit of of the result. 
Result so far: 42
Subtract 16 from 22 to get 6.
Bring next digit (0) of the dividend behind the 6 and repeat the process: 60 / 8

Step 4:
8 goes into 60 7 times with a remainder of 4.
Write down 7 as next digit of of the result. 
Result so far: 427
Subtract 56 from 60 to get 4.

The final result is 427 with a remainder of 4.