We look at the division of 303198 by 21 
Let's see how many times 21 fits into 303198.

Going ahead to step 1:
21 goes into 3 0 times with a remainder of 3.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 3 to get 3.
Take the next digit (0) from the dividend and append it to 3, then repeat: 30 / 21

Step 2:
The number 21 fits into 30 1 times, leaving a remainder of 9.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Subtract 21 from 30 to get 9.
Include the next digit (3) from the dividend after 9, then repeat: 93 / 21

On to step 3:
93 divided by 21 is 4 with a remainder of 9.
Record the quotient 4 as the next digit in the result. 
Result so far: 14.0
Subtracting 84 from 93 leaves us with 9.
Append the next digit (1) from the dividend to 9 and continue with: 91 / 21

Moving on to step 4:
21 goes into 91 4 times with a remainder of 7.
Write down 4 as next digit of the result. 
Result so far: 144.0
Subtract 84 from 91 to get 7.
Include the next digit (9) from the dividend after 7, then repeat: 79 / 21

On to step 5:
When dividing 79 by 21, we get 3 with a remainder of 16.
Use 3 as the next digit of our solution. 
Result so far: 1443.0
Deduct 63 from 79 and we're left with 16.
Fetch the next digit (8) from the dividend, attach it to 16 and continue: 168 / 21

On to step 6:
When dividing 168 by 21, we get 8 with a remainder of 0.
Use 8 as the next digit of our solution. 
Result so far: 14438.0
If we subtract 168 from 168, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 7:
0 divided by 21 is 0 with a remainder of 0.
The next digit of our result is 0. 
Result so far: 14438.0
Deduct 0 from 0 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing to step 8:
0 divided by 21 is 0 with a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 14438.0
If we take 0 away from 0, we end up with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final outcome is 14438.0, with a leftover of 0.0.