We look at the division of 660242 by 21 
We want to divide 660242 by 21.

Step 1:
The number 21 fits into 6 0 times, leaving a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Append the next digit (6) from the dividend to 6 and continue with: 66 / 21

Step 2:
21 goes into 66 3 times with a remainder of 3.
Record the quotient 3 as the next digit in the result. 
Result so far: 3.0
Subtracting 63 from 66 leaves us with 3.
Fetch the next digit (0) from the dividend, attach it to 3 and continue: 30 / 21

Step 3:
The number 21 fits into 30 1 times, leaving a remainder of 9.
The number 1 becomes the next digit in our result. 
Result so far: 31.0
Subtracting 21 from 30 leaves us with 9.
Bring next digit (2) of the dividend behind the 9 and repeat the process: 92 / 21

Let's proceed to step 4:
When dividing 92 by 21, we get 4 with a remainder of 8.
Write down 4 as next digit of the result. 
Result so far: 314.0
If we take 84 away from 92, we end up with 8.
Grab the next digit (4) from the dividend, add it to 8, then carry on: 84 / 21

Advancing to step 5:
If we divide 84 by 21, we get 4 and a remainder of 0.
The number 4 becomes the next digit in our result. 
Result so far: 3144.0
If we take 84 away from 84, we end up with 0.
Bring next digit (2) of the dividend behind the 0 and repeat the process: 2 / 21

Advancing to step 6:
21 goes into 2 0 times with a remainder of 2.
Record the quotient 0 as the next digit in the result. 
Result so far: 31440.0
Subtracting 0 from 2 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:
21 can be fit into 20 0 times, resulting in a remainder of 20.
Record the quotient 0 as the next digit in the result. 
Result so far: 31440.0
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.

On to step 8:
200 divided by 21 is 9 with a remainder of 11.
The next digit of our result is 9. 
Result so far: 31440.09
Subtract 189 from 200 to 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.

Moving on to step 9:
If we divide 110 by 21, we get 5 and a remainder of 5.
The number 5 becomes the next digit in our result. 
Result so far: 31440.095
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.

Step 10:
When dividing 50 by 21, we get 2 with a remainder of 8.
The next digit of our result is 2. 
Result so far: 31440.0952
The remainder is 8 after subtracting 42 from 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Advancing to step 11:
21 goes into 80 3 times with a remainder of 17.
Put 3 as the next digit of the answer. 
Result so far: 31440.09523
Deduct 63 from 80 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.

Advancing to step 12:
The number 21 fits into 170 8 times, leaving a remainder of 2.
The next digit of our result is 8. 
Result so far: 31440.095238
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.

Advancing to step 13:
If we divide 20 by 21, we get 0 and a remainder of 20.
Record the quotient 0 as the next digit in the result. 
Result so far: 31440.095238
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.

Moving on to step 14:
21 can be fit into 200 9 times, resulting in a remainder of 11.
Record the quotient 9 as the next digit in the result. 
Result so far: 31440.09523809
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 result is 31440.09523809 with a remainder of 1.1e-08.