We're dividing 406366 by 21 
We're looking to find how many times 21 goes into 406366.

Moving on to step 1:
4 divided by 21 is 0 with a remainder of 4.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 4, we get 4.
Fetch the next digit (0) from the dividend, attach it to 4 and continue: 40 / 21

Moving on to step 2:
21 can be fit into 40 1 times, resulting in a remainder of 19.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Deduct 21 from 40 and we're left with 19.
Include the next digit (6) from the dividend after 19, then repeat: 196 / 21

Moving on to step 3:
21 goes into 196 9 times with a remainder of 7.
Use 9 as the next digit of our solution. 
Result so far: 19.0
Subtract 189 from 196 to get 7.
Fetch the next digit (3) from the dividend, attach it to 7 and continue: 73 / 21

Advancing to step 4:
21 can be fit into 73 3 times, resulting in a remainder of 10.
Use 3 as the next digit of our solution. 
Result so far: 193.0
If we take 63 away from 73, we end up with 10.
Append the next digit (6) from the dividend to 10 and continue with: 106 / 21

Going ahead to step 5:
If we divide 106 by 21, we get 5 and a remainder of 1.
Use 5 as the next digit of our solution. 
Result so far: 1935.0
Subtracting 105 from 106 leaves us with 1.
Bring next digit (6) of the dividend behind the 1 and repeat the process: 16 / 21

Going ahead to step 6:
When dividing 16 by 21, we get 0 with a remainder of 16.
The number 0 becomes the next digit in our result. 
Result so far: 19350.0
Subtract 0 from 16 to get 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Step 7:
21 goes into 160 7 times with a remainder of 13.
Use 7 as the next digit of our solution. 
Result so far: 19350.7
The remainder is 13 after subtracting 147 from 160.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Step 8:
21 goes into 130 6 times with a remainder of 4.
Record the quotient 6 as the next digit in the result. 
Result so far: 19350.76
Subtract 126 from 130 to get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Advancing to step 9:
If we divide 40 by 21, we get 1 and a remainder of 19.
The next digit of our result is 1. 
Result so far: 19350.761
Deduct 21 from 40 and we're left with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Advancing to step 10:
If we divide 190 by 21, we get 9 and a remainder of 1.
Write down 9 as next digit of the result. 
Result so far: 19350.7619
If we subtract 189 from 190, we get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Let's proceed to step 11:
21 goes into 10 0 times with a remainder of 10.
The next digit of our result is 0. 
Result so far: 19350.7619
If we take 0 away from 10, we end up with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 12:
When dividing 100 by 21, we get 4 with a remainder of 16.
Use 4 as the next digit of our solution. 
Result so far: 19350.761904
Deduct 84 from 100 and we're left with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

On to step 13:
21 can be fit into 160 7 times, resulting in a remainder of 13.
The number 7 becomes the next digit in our result. 
Result so far: 19350.7619047
Subtract 147 from 160 to get 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Let's proceed to step 14:
The number 21 fits into 130 6 times, leaving a remainder of 4.
The number 6 becomes the next digit in our result. 
Result so far: 19350.76190476
If we subtract 126 from 130, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

The final result is 19350.76190476 with a remainder of 4e-09.