87777 ÷ 7 = 12539 R4
We're going to perform division on 87777 with 7 as the divisor.

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 (7) of the dividend behind the 1 and repeat the process: 17 / 7

Step 2:
7 goes into 17 2 times with a remainder of 3.
Write down 2 as next digit of of the result. 
Result so far: 12
Subtract 14 from 17 to get 3.
Bring next digit (7) of the dividend behind the 3 and repeat the process: 37 / 7

Step 3:
7 goes into 37 5 times with a remainder of 2.
Write down 5 as next digit of of the result. 
Result so far: 125
Subtract 35 from 37 to get 2.
Bring next digit (7) of the dividend behind the 2 and repeat the process: 27 / 7

Step 4:
7 goes into 27 3 times with a remainder of 6.
Write down 3 as next digit of of the result. 
Result so far: 1253
Subtract 21 from 27 to get 6.
Bring next digit (7) of the dividend behind the 6 and repeat the process: 67 / 7

Step 5:
7 goes into 67 9 times with a remainder of 4.
Write down 9 as next digit of of the result. 
Result so far: 12539
Subtract 63 from 67 to get 4.

The final result is 12539 with a remainder of 4.