309557 divided by 21 
Our goal is to divide 309557 by 21.

Let's proceed to step 1:
If we divide 3 by 21, we get 0 and a remainder of 3.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 3 after subtracting 0 from 3.
Take the next digit (0) from the dividend and append it to 3, then repeat: 30 / 21

Advancing to step 2:
21 goes into 30 1 times with a remainder of 9.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
Subtracting 21 from 30 leaves us with 9.
Fetch the next digit (9) from the dividend, attach it to 9 and continue: 99 / 21

Step 3:
99 divided by 21 is 4 with a remainder of 15.
The number 4 becomes the next digit in our result. 
Result so far: 14.0
If we subtract 84 from 99, we get 15.
Append the next digit (5) from the dividend to 15 and continue with: 155 / 21

Step 4:
155 divided by 21 is 7 with a remainder of 8.
Write down 7 as next digit of the result. 
Result so far: 147.0
If we take 147 away from 155, we end up with 8.
Fetch the next digit (5) from the dividend, attach it to 8 and continue: 85 / 21

On to step 5:
If we divide 85 by 21, we get 4 and a remainder of 1.
Use 4 as the next digit of our solution. 
Result so far: 1474.0
The remainder is 1 after subtracting 84 from 85.
Bring next digit (7) of the dividend behind the 1 and repeat the process: 17 / 21

Let's proceed to step 6:
17 divided by 21 is 0 with a remainder of 17.
The number 0 becomes the next digit in our result. 
Result so far: 14740.0
Deduct 0 from 17 and we're left with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Let's proceed to step 7:
170 divided by 21 is 8 with a remainder of 2.
The number 8 becomes the next digit in our result. 
Result so far: 14740.8
If we subtract 168 from 170, we get 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 8:
When dividing 20 by 21, we get 0 with a remainder of 20.
Use 0 as the next digit of our solution. 
Result so far: 14740.8
Subtracting 0 from 20 leaves us 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.

Step 9:
The number 21 fits into 200 9 times, leaving a remainder of 11.
The next digit of our result is 9. 
Result so far: 14740.809
The remainder is 11 after subtracting 189 from 200.
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 10:
110 divided by 21 is 5 with a remainder of 5.
Put 5 as the next digit of the answer. 
Result so far: 14740.8095
Deduct 105 from 110 and we're left 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.

Going ahead to step 11:
The number 21 fits into 50 2 times, leaving a remainder of 8.
The next digit of our result is 2. 
Result so far: 14740.80952
If we take 42 away from 50, we end up 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 12:
21 goes into 80 3 times with a remainder of 17.
Write down 3 as next digit of the result. 
Result so far: 14740.809523
Subtracting 63 from 80 leaves us with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

On to step 13:
21 can be fit into 170 8 times, resulting in a remainder of 2.
Use 8 as the next digit of our solution. 
Result so far: 14740.8095238
The remainder is 2 after subtracting 168 from 170.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Moving on to step 14:
20 divided by 21 is 0 with a remainder of 20.
Record the quotient 0 as the next digit in the result. 
Result so far: 14740.8095238
Subtract 0 from 20 to 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.

The final outcome is 14740.8095238, with a leftover of 2e-08.