We're dividing 592809 by 21 
The aim is to understand the frequency of 21 in 592809.

Step 1:
When dividing 5 by 21, we get 0 with a remainder of 5.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Include the next digit (9) from the dividend after 5, then repeat: 59 / 21

Moving on to step 2:
59 divided by 21 is 2 with a remainder of 17.
Write down 2 as next digit of the result. 
Result so far: 2.0
Deduct 42 from 59 and we're left with 17.
Append the next digit (2) from the dividend to 17 and continue with: 172 / 21

Let's proceed to step 3:
If we divide 172 by 21, we get 8 and a remainder of 4.
Use 8 as the next digit of our solution. 
Result so far: 28.0
Subtract 168 from 172 to get 4.
Grab the next digit (8) from the dividend, add it to 4, then carry on: 48 / 21

Going ahead to step 4:
21 goes into 48 2 times with a remainder of 6.
Write down 2 as next digit of the result. 
Result so far: 282.0
Deduct 42 from 48 and we're left with 6.
Bring next digit (0) of the dividend behind the 6 and repeat the process: 60 / 21

Moving on to step 5:
21 goes into 60 2 times with a remainder of 18.
The next digit of our result is 2. 
Result so far: 2822.0
The remainder is 18 after subtracting 42 from 60.
Include the next digit (9) from the dividend after 18, then repeat: 189 / 21

On to step 6:
21 goes into 189 9 times with a remainder of 0.
Record the quotient 9 as the next digit in the result. 
Result so far: 28229.0
Deduct 189 from 189 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Moving on to step 7:
0 divided by 21 is 0 with a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 28229.0
Subtracting 0 from 0 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing to step 8:
0 divided by 21 is 0 with a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 28229.0
The remainder is 0 after subtracting 0 from 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Our division results in 28229.0 with a remaining 0.0.