428558 ÷ 21 
We want to divide 428558 by 21.

On to step 1:
4 divided by 21 is 0 with a remainder of 4.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 4 to get 4.
Include the next digit (2) from the dividend after 4, then repeat: 42 / 21

Advancing to step 2:
If we divide 42 by 21, we get 2 and a remainder of 0.
The next digit of our result is 2. 
Result so far: 2.0
If we subtract 42 from 42, we get 0.
Include the next digit (8) from the dividend after 0, then repeat: 8 / 21

On to step 3:
21 can be fit into 8 0 times, resulting in a remainder of 8.
Put 0 as the next digit of the answer. 
Result so far: 20.0
If we take 0 away from 8, we end up with 8.
Grab the next digit (5) from the dividend, add it to 8, then carry on: 85 / 21

Step 4:
21 goes into 85 4 times with a remainder of 1.
The next digit of our result is 4. 
Result so far: 204.0
If we subtract 84 from 85, we get 1.
Append the next digit (5) from the dividend to 1 and continue with: 15 / 21

Going ahead to step 5:
21 can be fit into 15 0 times, resulting in a remainder of 15.
Put 0 as the next digit of the answer. 
Result so far: 2040.0
Subtracting 0 from 15 leaves us with 15.
Bring next digit (8) of the dividend behind the 15 and repeat the process: 158 / 21

Let's proceed to step 6:
If we divide 158 by 21, we get 7 and a remainder of 11.
The number 7 becomes the next digit in our result. 
Result so far: 20407.0
Deduct 147 from 158 and we're left with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Advancing to step 7:
When dividing 110 by 21, we get 5 with a remainder of 5.
Use 5 as the next digit of our solution. 
Result so far: 20407.5
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.

Advancing to step 8:
If we divide 50 by 21, we get 2 and a remainder of 8.
Use 2 as the next digit of our solution. 
Result so far: 20407.52
If we subtract 42 from 50, we get 8.
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 9:
80 divided by 21 is 3 with a remainder of 17.
Write down 3 as next digit of the result. 
Result so far: 20407.523
The remainder is 17 after subtracting 63 from 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Going ahead to step 10:
170 divided by 21 is 8 with a remainder of 2.
Use 8 as the next digit of our solution. 
Result so far: 20407.5238
If we take 168 away from 170, we end up 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.

Going ahead to step 11:
If we divide 20 by 21, we get 0 and a remainder of 20.
Write down 0 as next digit of the result. 
Result so far: 20407.5238
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.

Step 12:
200 divided by 21 is 9 with a remainder of 11.
The next digit of our result is 9. 
Result so far: 20407.523809
If we take 189 away from 200, we end up with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Step 13:
21 goes into 110 5 times with a remainder of 5.
The next digit of our result is 5. 
Result so far: 20407.5238095
The remainder is 5 after subtracting 105 from 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Let's proceed to step 14:
When dividing 50 by 21, we get 2 with a remainder of 8.
The next digit of our result is 2. 
Result so far: 20407.52380952
Deduct 42 from 50 and we're left 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.

The final result is 20407.52380952 with a remainder of 8e-09.