603311 ÷ 21 
We want to divide 603311 by 21.

Moving on to step 1:
When dividing 6 by 21, we get 0 with a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 6 to get 6.
Append the next digit (0) from the dividend to 6 and continue with: 60 / 21

Advancing to step 2:
21 goes into 60 2 times with a remainder of 18.
Write down 2 as next digit of the result. 
Result so far: 2.0
If we take 42 away from 60, we end up with 18.
Bring next digit (3) of the dividend behind the 18 and repeat the process: 183 / 21

On to step 3:
The number 21 fits into 183 8 times, leaving a remainder of 15.
Put 8 as the next digit of the answer. 
Result so far: 28.0
Subtracting 168 from 183 leaves us with 15.
Take the next digit (3) from the dividend and append it to 15, then repeat: 153 / 21

Step 4:
21 goes into 153 7 times with a remainder of 6.
Put 7 as the next digit of the answer. 
Result so far: 287.0
If we subtract 147 from 153, we get 6.
Include the next digit (1) from the dividend after 6, then repeat: 61 / 21

Step 5:
The number 21 fits into 61 2 times, leaving a remainder of 19.
Put 2 as the next digit of the answer. 
Result so far: 2872.0
Deduct 42 from 61 and we're left with 19.
Append the next digit (1) from the dividend to 19 and continue with: 191 / 21

Let's proceed to step 6:
If we divide 191 by 21, we get 9 and a remainder of 2.
Record the quotient 9 as the next digit in the result. 
Result so far: 28729.0
Subtracting 189 from 191 leaves us with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Step 7:
If we divide 20 by 21, we get 0 and a remainder of 20.
The next digit of our result is 0. 
Result so far: 28729.0
If we subtract 0 from 20, we get 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

On to step 8:
The number 21 fits into 200 9 times, leaving a remainder of 11.
Write down 9 as next digit of the result. 
Result so far: 28729.09
If we subtract 189 from 200, we get 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Let's proceed to step 9:
21 goes into 110 5 times with a remainder of 5.
The next digit of our result is 5. 
Result so far: 28729.095
Subtracting 105 from 110 leaves us with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Advancing to step 10:
21 can be fit into 50 2 times, resulting in a remainder of 8.
Put 2 as the next digit of the answer. 
Result so far: 28729.0952
Subtracting 42 from 50 leaves us with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

On to step 11:
80 divided by 21 is 3 with a remainder of 17.
Put 3 as the next digit of the answer. 
Result so far: 28729.09523
Subtract 63 from 80 to get 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Moving on to step 12:
21 can be fit into 170 8 times, resulting in a remainder of 2.
The number 8 becomes the next digit in our result. 
Result so far: 28729.095238
Deduct 168 from 170 and we're left with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Step 13:
The number 21 fits into 20 0 times, leaving a remainder of 20.
The number 0 becomes the next digit in our result. 
Result so far: 28729.095238
Deduct 0 from 20 and we're left with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Going ahead to step 14:
21 goes into 200 9 times with a remainder of 11.
The number 9 becomes the next digit in our result. 
Result so far: 28729.09523809
If we subtract 189 from 200, we get 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

The final outcome is 28729.09523809, with a leftover of 1.1e-08.