909423 divided by 21 
We're looking to find how many times 21 goes into 909423.

On to step 1:
9 divided by 21 is 0 with a remainder of 9.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 9 after subtracting 0 from 9.
Fetch the next digit (0) from the dividend, attach it to 9 and continue: 90 / 21

Moving on to step 2:
If we divide 90 by 21, we get 4 and a remainder of 6.
The next digit of our result is 4. 
Result so far: 4.0
Subtract 84 from 90 to get 6.
Take the next digit (9) from the dividend and append it to 6, then repeat: 69 / 21

Moving on to step 3:
21 can be fit into 69 3 times, resulting in a remainder of 6.
Put 3 as the next digit of the answer. 
Result so far: 43.0
Subtract 63 from 69 to get 6.
Include the next digit (4) from the dividend after 6, then repeat: 64 / 21

Going ahead to step 4:
The number 21 fits into 64 3 times, leaving a remainder of 1.
The number 3 becomes the next digit in our result. 
Result so far: 433.0
Deduct 63 from 64 and we're left with 1.
Grab the next digit (2) from the dividend, add it to 1, then carry on: 12 / 21

Step 5:
If we divide 12 by 21, we get 0 and a remainder of 12.
The number 0 becomes the next digit in our result. 
Result so far: 4330.0
Subtract 0 from 12 to get 12.
Take the next digit (3) from the dividend and append it to 12, then repeat: 123 / 21

Going ahead to step 6:
When dividing 123 by 21, we get 5 with a remainder of 18.
Write down 5 as next digit of the result. 
Result so far: 43305.0
Subtracting 105 from 123 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.

On to step 7:
The number 21 fits into 180 8 times, leaving a remainder of 12.
Put 8 as the next digit of the answer. 
Result so far: 43305.8
The remainder is 12 after subtracting 168 from 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Moving on to step 8:
120 divided by 21 is 5 with a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 43305.85
The remainder is 15 after subtracting 105 from 120.
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:
When dividing 150 by 21, we get 7 with a remainder of 3.
The next digit of our result is 7. 
Result so far: 43305.857
If we subtract 147 from 150, we 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.

Advancing to step 10:
21 goes into 30 1 times with a remainder of 9.
The number 1 becomes the next digit in our result. 
Result so far: 43305.8571
Subtracting 21 from 30 leaves us with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Advancing to step 11:
21 can be fit into 90 4 times, resulting in a remainder of 6.
Write down 4 as next digit of the result. 
Result so far: 43305.85714
Deduct 84 from 90 and we're left with 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.
The next digit of our result is 2. 
Result so far: 43305.857142
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 13:
21 can be fit into 180 8 times, resulting in a remainder of 12.
Write down 8 as next digit of the result. 
Result so far: 43305.8571428
The remainder is 12 after subtracting 168 from 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Step 14:
21 can be fit into 120 5 times, resulting in a remainder of 15.
Put 5 as the next digit of the answer. 
Result so far: 43305.85714285
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.

After the division, we end up with 43305.85714285 and a remainder of 1.5e-08.