16851 ÷ 4 = 4212 R3
We're going to perform division on 16851 with 4 as the divisor.

Step 1:
4 goes into 1 0 times with a remainder of 1.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 1 to get 1.
Bring next digit (6) of the dividend behind the 1 and repeat the process: 16 / 4

Step 2:
4 goes into 16 4 times with a remainder of 0.
Write down 4 as next digit of of the result. 
Result so far: 4
Subtract 16 from 16 to get 0.
Bring next digit (8) of the dividend behind the 0 and repeat the process: 8 / 4

Step 3:
4 goes into 8 2 times with a remainder of 0.
Write down 2 as next digit of of the result. 
Result so far: 42
Subtract 8 from 8 to get 0.
Bring next digit (5) of the dividend behind the 0 and repeat the process: 5 / 4

Step 4:
4 goes into 5 1 times with a remainder of 1.
Write down 1 as next digit of of the result. 
Result so far: 421
Subtract 4 from 5 to get 1.
Bring next digit (1) of the dividend behind the 1 and repeat the process: 11 / 4

Step 5:
4 goes into 11 2 times with a remainder of 3.
Write down 2 as next digit of of the result. 
Result so far: 4212
Subtract 8 from 11 to get 3.

The final result is 4212 with a remainder of 3.