13603 ÷ 9 = 1511 R4
Let's divide 13603 by 9.

Step 1:
9 goes into 1 0 times with a remainder of 1.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 1 to get 1.
Bring next digit (3) of the dividend behind the 1 and repeat the process: 13 / 9

Step 2:
9 goes into 13 1 times with a remainder of 4.
Write down 1 as next digit of of the result. 
Result so far: 1
Subtract 9 from 13 to get 4.
Bring next digit (6) of the dividend behind the 4 and repeat the process: 46 / 9

Step 3:
9 goes into 46 5 times with a remainder of 1.
Write down 5 as next digit of of the result. 
Result so far: 15
Subtract 45 from 46 to get 1.
Bring next digit (0) of the dividend behind the 1 and repeat the process: 10 / 9

Step 4:
9 goes into 10 1 times with a remainder of 1.
Write down 1 as next digit of of the result. 
Result so far: 151
Subtract 9 from 10 to get 1.
Bring next digit (3) of the dividend behind the 1 and repeat the process: 13 / 9

Step 5:
9 goes into 13 1 times with a remainder of 4.
Write down 1 as next digit of of the result. 
Result so far: 1511
Subtract 9 from 13 to get 4.

The final result is 1511 with a remainder of 4.