We're dividing 394952 by 21 
The aim is to understand the frequency of 21 in 394952.

Step 1:
21 can be fit into 3 0 times, resulting in a remainder of 3.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 3 after subtracting 0 from 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 21

Moving on to step 2:
21 can be fit into 39 1 times, resulting in a remainder of 18.
Use 1 as the next digit of our solution. 
Result so far: 1.0
If we take 21 away from 39, we end up with 18.
Include the next digit (4) from the dividend after 18, then repeat: 184 / 21

On to step 3:
184 divided by 21 is 8 with a remainder of 16.
Use 8 as the next digit of our solution. 
Result so far: 18.0
If we take 168 away from 184, we end up with 16.
Include the next digit (9) from the dividend after 16, then repeat: 169 / 21

Step 4:
When dividing 169 by 21, we get 8 with a remainder of 1.
Write down 8 as next digit of the result. 
Result so far: 188.0
Subtracting 168 from 169 leaves us with 1.
Bring next digit (5) of the dividend behind the 1 and repeat the process: 15 / 21

Advancing to step 5:
The number 21 fits into 15 0 times, leaving a remainder of 15.
Write down 0 as next digit of the result. 
Result so far: 1880.0
Subtract 0 from 15 to get 15.
Grab the next digit (2) from the dividend, add it to 15, then carry on: 152 / 21

Going ahead to step 6:
21 can be fit into 152 7 times, resulting in a remainder of 5.
Write down 7 as next digit of the result. 
Result so far: 18807.0
The remainder is 5 after subtracting 147 from 152.
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 7:
The number 21 fits into 50 2 times, leaving a remainder of 8.
Record the quotient 2 as the next digit in the result. 
Result so far: 18807.2
The remainder is 8 after subtracting 42 from 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Moving on to step 8:
When dividing 80 by 21, we get 3 with a remainder of 17.
Use 3 as the next digit of our solution. 
Result so far: 18807.23
Deduct 63 from 80 and we're left with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Going ahead to step 9:
If we divide 170 by 21, we get 8 and a remainder of 2.
The number 8 becomes the next digit in our result. 
Result so far: 18807.238
Subtracting 168 from 170 leaves us with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

On to step 10:
The number 21 fits into 20 0 times, leaving a remainder of 20.
Put 0 as the next digit of the answer. 
Result so far: 18807.238
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.

Let's proceed to step 11:
200 divided by 21 is 9 with a remainder of 11.
The number 9 becomes the next digit in our result. 
Result so far: 18807.23809
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.

On to step 12:
110 divided by 21 is 5 with a remainder of 5.
Record the quotient 5 as the next digit in the result. 
Result so far: 18807.238095
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 13:
50 divided by 21 is 2 with a remainder of 8.
The number 2 becomes the next digit in our result. 
Result so far: 18807.2380952
Subtracting 42 from 50 leaves us with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Advancing to step 14:
21 goes into 80 3 times with a remainder of 17.
The number 3 becomes the next digit in our result. 
Result so far: 18807.23809523
Deduct 63 from 80 and we're left with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

The final outcome is 18807.23809523, with a leftover of 1.7e-08.