78129 ÷ 7 = 11161 R2
Let's divide 78129 by 7.

Step 1:
7 goes into 7 1 times with a remainder of 0.
Write down 1 as next digit of of the result. 
Result so far: 1
Subtract 7 from 7 to get 0.
Bring next digit (8) of the dividend behind the 0 and repeat the process: 8 / 7

Step 2:
7 goes into 8 1 times with a remainder of 1.
Write down 1 as next digit of of the result. 
Result so far: 11
Subtract 7 from 8 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: 111
Subtract 7 from 11 to get 4.
Bring next digit (2) of the dividend behind the 4 and repeat the process: 42 / 7

Step 4:
7 goes into 42 6 times with a remainder of 0.
Write down 6 as next digit of of the result. 
Result so far: 1116
Subtract 42 from 42 to get 0.
Bring next digit (9) of the dividend behind the 0 and repeat the process: 9 / 7

Step 5:
7 goes into 9 1 times with a remainder of 2.
Write down 1 as next digit of of the result. 
Result so far: 11161
Subtract 7 from 9 to get 2.

The final result is 11161 with a remainder of 2.