2121 ÷ 6 = 353 R3
We're going to perform division on 2121 with 6 as the divisor.

Step 1:
6 goes into 2 0 times with a remainder of 2.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 2 to get 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 6

Step 2:
6 goes into 21 3 times with a remainder of 3.
Write down 3 as next digit of of the result. 
Result so far: 3
Subtract 18 from 21 to get 3.
Bring next digit (2) of the dividend behind the 3 and repeat the process: 32 / 6

Step 3:
6 goes into 32 5 times with a remainder of 2.
Write down 5 as next digit of of the result. 
Result so far: 35
Subtract 30 from 32 to get 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 6

Step 4:
6 goes into 21 3 times with a remainder of 3.
Write down 3 as next digit of of the result. 
Result so far: 353
Subtract 18 from 21 to get 3.

The final result is 353 with a remainder of 3.