We're dividing 403259 by 21 
We're looking to find how many times 21 goes into 403259.

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.
Bring next digit (0) of the dividend behind the 4 and repeat the process: 40 / 21

Moving on to step 2:
When dividing 40 by 21, we get 1 with a remainder of 19.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
The remainder is 19 after subtracting 21 from 40.
Fetch the next digit (3) from the dividend, attach it to 19 and continue: 193 / 21

Advancing to step 3:
If we divide 193 by 21, we get 9 and a remainder of 4.
The next digit of our result is 9. 
Result so far: 19.0
Deduct 189 from 193 and we're left with 4.
Append the next digit (2) from the dividend to 4 and continue with: 42 / 21

Step 4:
When dividing 42 by 21, we get 2 with a remainder of 0.
Put 2 as the next digit of the answer. 
Result so far: 192.0
The remainder is 0 after subtracting 42 from 42.
Include the next digit (5) from the dividend after 0, then repeat: 5 / 21

Advancing to step 5:
If we divide 5 by 21, we get 0 and a remainder of 5.
Put 0 as the next digit of the answer. 
Result so far: 1920.0
If we subtract 0 from 5, we get 5.
Bring next digit (9) of the dividend behind the 5 and repeat the process: 59 / 21

On to step 6:
21 goes into 59 2 times with a remainder of 17.
The number 2 becomes the next digit in our result. 
Result so far: 19202.0
The remainder is 17 after subtracting 42 from 59.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Step 7:
If we divide 170 by 21, we get 8 and a remainder of 2.
Write down 8 as next digit of the result. 
Result so far: 19202.8
Subtracting 168 from 170 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.

Advancing to step 8:
If we divide 20 by 21, we get 0 and a remainder of 20.
Use 0 as the next digit of our solution. 
Result so far: 19202.8
Subtracting 0 from 20 leaves us 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.

Moving on to step 9:
21 can be fit into 200 9 times, resulting in a remainder of 11.
Write down 9 as next digit of the result. 
Result so far: 19202.809
The remainder is 11 after subtracting 189 from 200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Step 10:
When dividing 110 by 21, we get 5 with a remainder of 5.
Record the quotient 5 as the next digit in the result. 
Result so far: 19202.8095
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.

On to step 11:
21 can be fit into 50 2 times, resulting in a remainder of 8.
Record the quotient 2 as the next digit in the result. 
Result so far: 19202.80952
If we take 42 away from 50, we end up 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.

Moving on to step 12:
The number 21 fits into 80 3 times, leaving a remainder of 17.
Record the quotient 3 as the next digit in the result. 
Result so far: 19202.809523
Subtracting 63 from 80 leaves us 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.

Going ahead to step 13:
The number 21 fits into 170 8 times, leaving a remainder of 2.
Record the quotient 8 as the next digit in the result. 
Result so far: 19202.8095238
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 14:
21 can be fit into 20 0 times, resulting in a remainder of 20.
Put 0 as the next digit of the answer. 
Result so far: 19202.8095238
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.

Our division results in 19202.8095238 with a remaining 2e-08.