We're dividing 9905823 by 21 
The aim is to understand the frequency of 21 in 9905823.

Moving on to step 1:
If we divide 9 by 21, we get 0 and a remainder of 9.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 9, we get 9.
Bring next digit (9) of the dividend behind the 9 and repeat the process: 99 / 21

Step 2:
If we divide 99 by 21, we get 4 and a remainder of 15.
Use 4 as the next digit of our solution. 
Result so far: 4.0
Deduct 84 from 99 and we're left with 15.
Fetch the next digit (0) from the dividend, attach it to 15 and continue: 150 / 21

Step 3:
21 goes into 150 7 times with a remainder of 3.
Use 7 as the next digit of our solution. 
Result so far: 47.0
Subtract 147 from 150 to get 3.
Bring next digit (5) of the dividend behind the 3 and repeat the process: 35 / 21

On to step 4:
21 can be fit into 35 1 times, resulting in a remainder of 14.
Use 1 as the next digit of our solution. 
Result so far: 471.0
If we subtract 21 from 35, we get 14.
Fetch the next digit (8) from the dividend, attach it to 14 and continue: 148 / 21

On to step 5:
When dividing 148 by 21, we get 7 with a remainder of 1.
The next digit of our result is 7. 
Result so far: 4717.0
Subtracting 147 from 148 leaves us with 1.
Include the next digit (2) from the dividend after 1, then repeat: 12 / 21

Going ahead to step 6:
21 can be fit into 12 0 times, resulting in a remainder of 12.
The next digit of our result is 0. 
Result so far: 47170.0
If we subtract 0 from 12, we get 12.
Take the next digit (3) from the dividend and append it to 12, then repeat: 123 / 21

Let's proceed to step 7:
The number 21 fits into 123 5 times, leaving a remainder of 18.
The number 5 becomes the next digit in our result. 
Result so far: 471705.0
If we subtract 105 from 123, we 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.

Going ahead to step 8:
21 goes into 180 8 times with a remainder of 12.
The next digit of our result is 8. 
Result so far: 471705.8
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 9:
When dividing 120 by 21, we get 5 with a remainder of 15.
Record the quotient 5 as the next digit in the result. 
Result so far: 471705.85
Deduct 105 from 120 and we're left with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Let's proceed to step 10:
150 divided by 21 is 7 with a remainder of 3.
Put 7 as the next digit of the answer. 
Result so far: 471705.857
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.

Going ahead to step 11:
21 can be fit into 30 1 times, resulting in a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 471705.8571
If we take 21 away from 30, we end up 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.

On to step 12:
When dividing 90 by 21, we get 4 with a remainder of 6.
The next digit of our result is 4. 
Result so far: 471705.85714
If we take 84 away from 90, we end up 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.

Let's proceed to step 13:
21 goes into 60 2 times with a remainder of 18.
Use 2 as the next digit of our solution. 
Result so far: 471705.857142
If we take 42 away from 60, we end up 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.

Moving on to step 14:
The number 21 fits into 180 8 times, leaving a remainder of 12.
The number 8 becomes the next digit in our result. 
Result so far: 471705.8571428
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.

Let's proceed to step 15:
120 divided by 21 is 5 with a remainder of 15.
Record the quotient 5 as the next digit in the result. 
Result so far: 471705.85714285
If we take 105 away from 120, we end up with 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 outcome is 471705.85714285, with a leftover of 1.5e-08.