We're dividing 609301 by 21 
The aim is to understand the frequency of 21 in 609301.

Moving on to step 1:
If we divide 6 by 21, we get 0 and a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Append the next digit (0) from the dividend to 6 and continue with: 60 / 21

Step 2:
When dividing 60 by 21, we get 2 with a remainder of 18.
Write down 2 as next digit of the result. 
Result so far: 2.0
If we subtract 42 from 60, we get 18.
Bring next digit (9) of the dividend behind the 18 and repeat the process: 189 / 21

Step 3:
189 divided by 21 is 9 with a remainder of 0.
Put 9 as the next digit of the answer. 
Result so far: 29.0
Subtract 189 from 189 to get 0.
Include the next digit (3) from the dividend after 0, then repeat: 3 / 21

Let's proceed to step 4:
3 divided by 21 is 0 with a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 290.0
The remainder is 3 after subtracting 0 from 3.
Fetch the next digit (0) from the dividend, attach it to 3 and continue: 30 / 21

Going ahead to step 5:
If we divide 30 by 21, we get 1 and a remainder of 9.
The next digit of our result is 1. 
Result so far: 2901.0
Subtracting 21 from 30 leaves us with 9.
Take the next digit (1) from the dividend and append it to 9, then repeat: 91 / 21

Moving on to step 6:
21 goes into 91 4 times with a remainder of 7.
The next digit of our result is 4. 
Result so far: 29014.0
The remainder is 7 after subtracting 84 from 91.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Let's proceed to step 7:
If we divide 70 by 21, we get 3 and a remainder of 7.
Use 3 as the next digit of our solution. 
Result so far: 29014.3
Deduct 63 from 70 and we're left with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Advancing to step 8:
If we divide 70 by 21, we get 3 and a remainder of 7.
The number 3 becomes the next digit in our result. 
Result so far: 29014.33
If we take 63 away from 70, we end up with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

The final result is 29014.33 with a remainder of 0.007.