We're dividing 470923 by 21 
The aim is to understand the frequency of 21 in 470923.

Step 1:
If we divide 4 by 21, we get 0 and a remainder of 4.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 4, we end up with 4.
Include the next digit (7) from the dividend after 4, then repeat: 47 / 21

Advancing to step 2:
21 can be fit into 47 2 times, resulting in a remainder of 5.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
Subtracting 42 from 47 leaves us with 5.
Include the next digit (0) from the dividend after 5, then repeat: 50 / 21

Advancing to step 3:
21 goes into 50 2 times with a remainder of 8.
Use 2 as the next digit of our solution. 
Result so far: 22.0
Subtract 42 from 50 to get 8.
Take the next digit (9) from the dividend and append it to 8, then repeat: 89 / 21

On to step 4:
21 goes into 89 4 times with a remainder of 5.
The number 4 becomes the next digit in our result. 
Result so far: 224.0
Subtracting 84 from 89 leaves us with 5.
Bring next digit (2) of the dividend behind the 5 and repeat the process: 52 / 21

Moving on to step 5:
21 can be fit into 52 2 times, resulting in a remainder of 10.
Use 2 as the next digit of our solution. 
Result so far: 2242.0
The remainder is 10 after subtracting 42 from 52.
Fetch the next digit (3) from the dividend, attach it to 10 and continue: 103 / 21

Moving on to step 6:
The number 21 fits into 103 4 times, leaving a remainder of 19.
Put 4 as the next digit of the answer. 
Result so far: 22424.0
Deduct 84 from 103 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.

Step 7:
21 goes into 190 9 times with a remainder of 1.
Write down 9 as next digit of the result. 
Result so far: 22424.9
Deduct 189 from 190 and we're left with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

On to step 8:
If we divide 10 by 21, we get 0 and a remainder of 10.
Put 0 as the next digit of the answer. 
Result so far: 22424.9
Deduct 0 from 10 and we're left 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.

Advancing to step 9:
If we divide 100 by 21, we get 4 and a remainder of 16.
Put 4 as the next digit of the answer. 
Result so far: 22424.904
If we take 84 away from 100, we end up 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.

Step 10:
160 divided by 21 is 7 with a remainder of 13.
Put 7 as the next digit of the answer. 
Result so far: 22424.9047
If we subtract 147 from 160, we 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.

Advancing to step 11:
The number 21 fits into 130 6 times, leaving a remainder of 4.
The next digit of our result is 6. 
Result so far: 22424.90476
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.

On to step 12:
21 can be fit into 40 1 times, resulting in a remainder of 19.
Record the quotient 1 as the next digit in the result. 
Result so far: 22424.904761
Subtract 21 from 40 to get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Let's proceed to step 13:
When dividing 190 by 21, we get 9 with a remainder of 1.
Use 9 as the next digit of our solution. 
Result so far: 22424.9047619
Subtract 189 from 190 to 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.

On to step 14:
If we divide 10 by 21, we get 0 and a remainder of 10.
Use 0 as the next digit of our solution. 
Result so far: 22424.9047619
Subtract 0 from 10 to get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

In conclusion, the division gives 22424.9047619 with a balance of 1e-08.