23603 ÷ 4 = 5900 R3
Alright, let's work through the division of 23603 by 4 step by step.

Step 1:
4 goes into 2 0 times with a remainder of 2.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 2 to get 2.
Bring next digit (3) of the dividend behind the 2 and repeat the process: 23 / 4

Step 2:
4 goes into 23 5 times with a remainder of 3.
Write down 5 as next digit of of the result. 
Result so far: 5
Subtract 20 from 23 to get 3.
Bring next digit (6) of the dividend behind the 3 and repeat the process: 36 / 4

Step 3:
4 goes into 36 9 times with a remainder of 0.
Write down 9 as next digit of of the result. 
Result so far: 59
Subtract 36 from 36 to get 0.
Bring next digit (0) of the dividend behind the 0 and repeat the process: 0 / 4

Step 4:
4 goes into 0 0 times with a remainder of 0.
Write down 0 as next digit of of the result. 
Result so far: 590
Subtract 0 from 0 to get 0.
Bring next digit (3) of the dividend behind the 0 and repeat the process: 3 / 4

Step 5:
4 goes into 3 0 times with a remainder of 3.
Write down 0 as next digit of of the result. 
Result so far: 5900
Subtract 0 from 3 to get 3.

The final result is 5900 with a remainder of 3.