30603 ÷ 6 = 5100 R3
Alright, let's work through the division of 30603 by 6 step by step.

Step 1:
6 goes into 3 0 times with a remainder of 3.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 3 to get 3.
Bring next digit (0) of the dividend behind the 3 and repeat the process: 30 / 6

Step 2:
6 goes into 30 5 times with a remainder of 0.
Write down 5 as next digit of of the result. 
Result so far: 5
Subtract 30 from 30 to get 0.
Bring next digit (6) of the dividend behind the 0 and repeat the process: 6 / 6

Step 3:
6 goes into 6 1 times with a remainder of 0.
Write down 1 as next digit of of the result. 
Result so far: 51
Subtract 6 from 6 to get 0.
Bring next digit (0) of the dividend behind the 0 and repeat the process: 0 / 6

Step 4:
6 goes into 0 0 times with a remainder of 0.
Write down 0 as next digit of of the result. 
Result so far: 510
Subtract 0 from 0 to get 0.
Bring next digit (3) of the dividend behind the 0 and repeat the process: 3 / 6

Step 5:
6 goes into 3 0 times with a remainder of 3.
Write down 0 as next digit of of the result. 
Result so far: 5100
Subtract 0 from 3 to get 3.

The final result is 5100 with a remainder of 3.