We look at the division of 843506 by 21 
We want to figure out the number of times 843506 can be divided by 21.

Step 1:
When dividing 8 by 21, we get 0 with a remainder of 8.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we subtract 0 from 8, we get 8.
Include the next digit (4) from the dividend after 8, then repeat: 84 / 21

Let's proceed to step 2:
The number 21 fits into 84 4 times, leaving a remainder of 0.
Record the quotient 4 as the next digit in the result. 
Result so far: 4.0
Subtract 84 from 84 to get 0.
Include the next digit (3) from the dividend after 0, then repeat: 3 / 21

On to step 3:
21 can be fit into 3 0 times, resulting in a remainder of 3.
Write down 0 as next digit of the result. 
Result so far: 40.0
Subtract 0 from 3 to get 3.
Append the next digit (5) from the dividend to 3 and continue with: 35 / 21

Advancing to step 4:
21 goes into 35 1 times with a remainder of 14.
Write down 1 as next digit of the result. 
Result so far: 401.0
Subtracting 21 from 35 leaves us with 14.
Take the next digit (0) from the dividend and append it to 14, then repeat: 140 / 21

Advancing to step 5:
When dividing 140 by 21, we get 6 with a remainder of 14.
Write down 6 as next digit of the result. 
Result so far: 4016.0
If we subtract 126 from 140, we get 14.
Append the next digit (6) from the dividend to 14 and continue with: 146 / 21

Step 6:
When dividing 146 by 21, we get 6 with a remainder of 20.
The number 6 becomes the next digit in our result. 
Result so far: 40166.0
Subtract 126 from 146 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.

On to step 7:
21 can be fit into 200 9 times, resulting in a remainder of 11.
The number 9 becomes the next digit in our result. 
Result so far: 40166.9
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.

Going ahead to step 8:
When dividing 110 by 21, we get 5 with a remainder of 5.
Put 5 as the next digit of the answer. 
Result so far: 40166.95
If we take 105 away from 110, we end up 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.

Let's proceed to step 9:
21 goes into 50 2 times with a remainder of 8.
The number 2 becomes the next digit in our result. 
Result so far: 40166.952
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.

Going ahead to step 10:
The number 21 fits into 80 3 times, leaving a remainder of 17.
The number 3 becomes the next digit in our result. 
Result so far: 40166.9523
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.

On to step 11:
21 goes into 170 8 times with a remainder of 2.
Use 8 as the next digit of our solution. 
Result so far: 40166.95238
If we subtract 168 from 170, we get 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 12:
When dividing 20 by 21, we get 0 with a remainder of 20.
Record the quotient 0 as the next digit in the result. 
Result so far: 40166.95238
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 13:
21 goes into 200 9 times with a remainder of 11.
Record the quotient 9 as the next digit in the result. 
Result so far: 40166.9523809
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.

On to step 14:
When dividing 110 by 21, we get 5 with a remainder of 5.
Write down 5 as next digit of the result. 
Result so far: 40166.95238095
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.

Our division results in 40166.95238095 with a remaining 5e-09.