8603 ÷ 5 = 1720 R3
No problem, we've got 8603 and 5 for the division.

Step 1:
5 goes into 8 1 times with a remainder of 3.
Write down 1 as next digit of of the result. 
Result so far: 1
Subtract 5 from 8 to get 3.
Bring next digit (6) of the dividend behind the 3 and repeat the process: 36 / 5

Step 2:
5 goes into 36 7 times with a remainder of 1.
Write down 7 as next digit of of the result. 
Result so far: 17
Subtract 35 from 36 to get 1.
Bring next digit (0) of the dividend behind the 1 and repeat the process: 10 / 5

Step 3:
5 goes into 10 2 times with a remainder of 0.
Write down 2 as next digit of of the result. 
Result so far: 172
Subtract 10 from 10 to get 0.
Bring next digit (3) of the dividend behind the 0 and repeat the process: 3 / 5

Step 4:
5 goes into 3 0 times with a remainder of 3.
Write down 0 as next digit of of the result. 
Result so far: 1720
Subtract 0 from 3 to get 3.

The final result is 1720 with a remainder of 3.