Let's divide 398010 by 21
Let's see how many times 21 fits into 398010.

Step 1:
3 divided by 21 is 0 with a remainder of 3.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 3 to get 3.
Fetch the next digit (9) from the dividend, attach it to 3 and continue: 39 / 21

On to step 2:
If we divide 39 by 21, we get 1 and a remainder of 18.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Subtracting 21 from 39 leaves us with 18.
Append the next digit (8) from the dividend to 18 and continue with: 188 / 21

On to step 3:
If we divide 188 by 21, we get 8 and a remainder of 20.
Write down 8 as next digit of the result. 
Result so far: 18.0
If we subtract 168 from 188, we get 20.
Append the next digit (0) from the dividend to 20 and continue with: 200 / 21

Going ahead to step 4:
200 divided by 21 is 9 with a remainder of 11.
Put 9 as the next digit of the answer. 
Result so far: 189.0
Subtract 189 from 200 to get 11.
Include the next digit (1) from the dividend after 11, then repeat: 111 / 21

On to step 5:
21 goes into 111 5 times with a remainder of 6.
Write down 5 as next digit of the result. 
Result so far: 1895.0
Deduct 105 from 111 and we're left with 6.
Grab the next digit (0) from the dividend, add it to 6, then carry on: 60 / 21

Advancing to step 6:
The number 21 fits into 60 2 times, leaving a remainder of 18.
The number 2 becomes the next digit in our result. 
Result so far: 18952.0
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.

Moving on to step 7:
If we divide 180 by 21, we get 8 and a remainder of 12.
Put 8 as the next digit of the answer. 
Result so far: 18952.8
Subtracting 168 from 180 leaves us 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.

Going ahead to step 8:
When dividing 120 by 21, we get 5 with a remainder of 15.
The next digit of our result is 5. 
Result so far: 18952.85
Subtract 105 from 120 to get 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 9:
21 goes into 150 7 times with a remainder of 3.
Record the quotient 7 as the next digit in the result. 
Result so far: 18952.857
Subtract 147 from 150 to 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.

On to step 10:
If we divide 30 by 21, we get 1 and a remainder of 9.
Record the quotient 1 as the next digit in the result. 
Result so far: 18952.8571
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 11:
If we divide 90 by 21, we get 4 and a remainder of 6.
Write down 4 as next digit of the result. 
Result so far: 18952.85714
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.

Advancing to step 12:
If we divide 60 by 21, we get 2 and a remainder of 18.
Use 2 as the next digit of our solution. 
Result so far: 18952.857142
Subtracting 42 from 60 leaves us with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Step 13:
21 goes into 180 8 times with a remainder of 12.
Record the quotient 8 as the next digit in the result. 
Result so far: 18952.8571428
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.

On to step 14:
The number 21 fits into 120 5 times, leaving a remainder of 15.
Put 5 as the next digit of the answer. 
Result so far: 18952.85714285
Subtract 105 from 120 to get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

The final result is 18952.85714285 with a remainder of 1.5e-08.