Let's divide 428661 by 21
We want to figure out the number of times 428661 can be divided by 21.

Going ahead to step 1:
21 can be fit into 4 0 times, resulting in a remainder of 4.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 4 after subtracting 0 from 4.
Take the next digit (2) from the dividend and append it to 4, then repeat: 42 / 21

Going ahead to step 2:
When dividing 42 by 21, we get 2 with a remainder of 0.
Record the quotient 2 as the next digit in the result. 
Result so far: 2.0
If we take 42 away from 42, we end up with 0.
Append the next digit (8) from the dividend to 0 and continue with: 8 / 21

Moving on to step 3:
21 goes into 8 0 times with a remainder of 8.
The number 0 becomes the next digit in our result. 
Result so far: 20.0
The remainder is 8 after subtracting 0 from 8.
Fetch the next digit (6) from the dividend, attach it to 8 and continue: 86 / 21

Advancing to step 4:
The number 21 fits into 86 4 times, leaving a remainder of 2.
Write down 4 as next digit of the result. 
Result so far: 204.0
If we subtract 84 from 86, we get 2.
Append the next digit (6) from the dividend to 2 and continue with: 26 / 21

Going ahead to step 5:
If we divide 26 by 21, we get 1 and a remainder of 5.
Record the quotient 1 as the next digit in the result. 
Result so far: 2041.0
The remainder is 5 after subtracting 21 from 26.
Include the next digit (1) from the dividend after 5, then repeat: 51 / 21

Going ahead to step 6:
When dividing 51 by 21, we get 2 with a remainder of 9.
Use 2 as the next digit of our solution. 
Result so far: 20412.0
If we take 42 away from 51, we end up 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.

On to step 7:
90 divided by 21 is 4 with a remainder of 6.
The number 4 becomes the next digit in our result. 
Result so far: 20412.4
Subtracting 84 from 90 leaves us 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.

Step 8:
60 divided by 21 is 2 with a remainder of 18.
The number 2 becomes the next digit in our result. 
Result so far: 20412.42
The remainder is 18 after subtracting 42 from 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Moving on to step 9:
21 can be fit into 180 8 times, resulting in a remainder of 12.
The next digit of our result is 8. 
Result so far: 20412.428
The remainder is 12 after subtracting 168 from 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Going ahead to step 10:
120 divided by 21 is 5 with a remainder of 15.
Put 5 as the next digit of the answer. 
Result so far: 20412.4285
Deduct 105 from 120 and we're left 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.

Step 11:
150 divided by 21 is 7 with a remainder of 3.
Write down 7 as next digit of the result. 
Result so far: 20412.42857
Deduct 147 from 150 and we're left 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.

Step 12:
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: 20412.428571
If we subtract 21 from 30, we get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Moving on to step 13:
The number 21 fits into 90 4 times, leaving a remainder of 6.
Use 4 as the next digit of our solution. 
Result so far: 20412.4285714
Subtract 84 from 90 to 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.

Going ahead to step 14:
21 can be fit into 60 2 times, resulting in a remainder of 18.
Put 2 as the next digit of the answer. 
Result so far: 20412.42857142
If we subtract 42 from 60, we 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.

In conclusion, the division gives 20412.42857142 with a balance of 1.8e-08.