5121 ÷ 6 = 853 R3
No problem, we've got 5121 and 6 for the division.

Step 1:
6 goes into 5 0 times with a remainder of 5.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 5 to get 5.
Bring next digit (1) of the dividend behind the 5 and repeat the process: 51 / 6

Step 2:
6 goes into 51 8 times with a remainder of 3.
Write down 8 as next digit of of the result. 
Result so far: 8
Subtract 48 from 51 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: 85
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: 853
Subtract 18 from 21 to get 3.

The final result is 853 with a remainder of 3.