77878 ÷ 7 = 11125 R3
Let's divide 77878 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 (7) of the dividend behind the 0 and repeat the process: 7 / 7

Step 2:
7 goes into 7 1 times with a remainder of 0.
Write down 1 as next digit of of the result. 
Result so far: 11
Subtract 7 from 7 to get 0.
Bring next digit (8) of the dividend behind the 0 and repeat the process: 8 / 7

Step 3:
7 goes into 8 1 times with a remainder of 1.
Write down 1 as next digit of of the result. 
Result so far: 111
Subtract 7 from 8 to get 1.
Bring next digit (7) of the dividend behind the 1 and repeat the process: 17 / 7

Step 4:
7 goes into 17 2 times with a remainder of 3.
Write down 2 as next digit of of the result. 
Result so far: 1112
Subtract 14 from 17 to get 3.
Bring next digit (8) of the dividend behind the 3 and repeat the process: 38 / 7

Step 5:
7 goes into 38 5 times with a remainder of 3.
Write down 5 as next digit of of the result. 
Result so far: 11125
Subtract 35 from 38 to get 3.

The final result is 11125 with a remainder of 3.