86503 ÷ 7 = 12357 R4
Let's divide 86503 by 7.

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 (6) of the dividend behind the 1 and repeat the process: 16 / 7

Step 2:
7 goes into 16 2 times with a remainder of 2.
Write down 2 as next digit of of the result. 
Result so far: 12
Subtract 14 from 16 to get 2.
Bring next digit (5) of the dividend behind the 2 and repeat the process: 25 / 7

Step 3:
7 goes into 25 3 times with a remainder of 4.
Write down 3 as next digit of of the result. 
Result so far: 123
Subtract 21 from 25 to get 4.
Bring next digit (0) of the dividend behind the 4 and repeat the process: 40 / 7

Step 4:
7 goes into 40 5 times with a remainder of 5.
Write down 5 as next digit of of the result. 
Result so far: 1235
Subtract 35 from 40 to get 5.
Bring next digit (3) of the dividend behind the 5 and repeat the process: 53 / 7

Step 5:
7 goes into 53 7 times with a remainder of 4.
Write down 7 as next digit of of the result. 
Result so far: 12357
Subtract 49 from 53 to get 4.

The final result is 12357 with a remainder of 4.