851 ÷ 7 = 121 R4
Alright, let's work through the division of 851 by 7 step by step.

Step 1:
7 goes into 8 1 times with a remainder of 1.
Write down 1 as next digit of of the result. 
Result so far: 1
Subtract 7 from 8 to get 1.
Bring next digit (5) of the dividend behind the 1 and repeat the process: 15 / 7

Step 2:
7 goes into 15 2 times with a remainder of 1.
Write down 2 as next digit of of the result. 
Result so far: 12
Subtract 14 from 15 to get 1.
Bring next digit (1) of the dividend behind the 1 and repeat the process: 11 / 7

Step 3:
7 goes into 11 1 times with a remainder of 4.
Write down 1 as next digit of of the result. 
Result so far: 121
Subtract 7 from 11 to get 4.

The final result is 121 with a remainder of 4.