We look at the division of 72957 by 21 
Let's see how many times 21 fits into 72957.

Step 1:
21 goes into 7 0 times with a remainder of 7.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 7 leaves us with 7.
Grab the next digit (2) from the dividend, add it to 7, then carry on: 72 / 21

Step 2:
21 can be fit into 72 3 times, resulting in a remainder of 9.
Put 3 as the next digit of the answer. 
Result so far: 3.0
Subtract 63 from 72 to get 9.
Fetch the next digit (9) from the dividend, attach it to 9 and continue: 99 / 21

Step 3:
21 goes into 99 4 times with a remainder of 15.
Record the quotient 4 as the next digit in the result. 
Result so far: 34.0
If we take 84 away from 99, we end up with 15.
Bring next digit (5) of the dividend behind the 15 and repeat the process: 155 / 21

Moving on to step 4:
155 divided by 21 is 7 with a remainder of 8.
The next digit of our result is 7. 
Result so far: 347.0
The remainder is 8 after subtracting 147 from 155.
Include the next digit (7) from the dividend after 8, then repeat: 87 / 21

Moving on to step 5:
21 can be fit into 87 4 times, resulting in a remainder of 3.
The number 4 becomes the next digit in our result. 
Result so far: 3474.0
If we take 84 away from 87, we end up with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Going ahead to step 6:
30 divided by 21 is 1 with a remainder of 9.
Put 1 as the next digit of the answer. 
Result so far: 3474.1
The remainder is 9 after subtracting 21 from 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

On to step 7:
21 can be fit into 90 4 times, resulting in a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 3474.14
If we take 84 away from 90, we end up with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Going ahead to step 8:
21 can be fit into 60 2 times, resulting in a remainder of 18.
Record the quotient 2 as the next digit in the result. 
Result so far: 3474.142
Subtract 42 from 60 to get 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Advancing to step 9:
21 goes into 180 8 times with a remainder of 12.
Write down 8 as next digit of the result. 
Result so far: 3474.1428
Deduct 168 from 180 and we're left with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Step 10:
The number 21 fits into 120 5 times, leaving a remainder of 15.
Write down 5 as next digit of the result. 
Result so far: 3474.14285
Subtracting 105 from 120 leaves us with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Advancing to step 11:
21 can be fit into 150 7 times, resulting in a remainder of 3.
Record the quotient 7 as the next digit in the result. 
Result so far: 3474.142857
If we subtract 147 from 150, we get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Let's proceed to step 12:
When dividing 30 by 21, we get 1 with a remainder of 9.
Use 1 as the next digit of our solution. 
Result so far: 3474.1428571
Subtracting 21 from 30 leaves us with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Going ahead to step 13:
The number 21 fits into 90 4 times, leaving a remainder of 6.
The next digit of our result is 4. 
Result so far: 3474.14285714
If we subtract 84 from 90, we get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

The final outcome is 3474.14285714, with a leftover of 6e-09.