We look at the division of 669067 by 21 
The aim is to understand the frequency of 21 in 669067.

Let's proceed to step 1:
21 can be fit into 6 0 times, resulting in a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 6 to get 6.
Take the next digit (6) from the dividend and append it to 6, then repeat: 66 / 21

Advancing to step 2:
If we divide 66 by 21, we get 3 and a remainder of 3.
Put 3 as the next digit of the answer. 
Result so far: 3.0
Subtracting 63 from 66 leaves us with 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 21

Let's proceed to step 3:
21 goes into 39 1 times with a remainder of 18.
Record the quotient 1 as the next digit in the result. 
Result so far: 31.0
Subtracting 21 from 39 leaves us with 18.
Include the next digit (0) from the dividend after 18, then repeat: 180 / 21

Going ahead to step 4:
When dividing 180 by 21, we get 8 with a remainder of 12.
Use 8 as the next digit of our solution. 
Result so far: 318.0
Subtract 168 from 180 to get 12.
Include the next digit (6) from the dividend after 12, then repeat: 126 / 21

Step 5:
21 goes into 126 6 times with a remainder of 0.
Put 6 as the next digit of the answer. 
Result so far: 3186.0
Subtracting 126 from 126 leaves us with 0.
Include the next digit (7) from the dividend after 0, then repeat: 7 / 21

Step 6:
7 divided by 21 is 0 with a remainder of 7.
The number 0 becomes the next digit in our result. 
Result so far: 31860.0
If we subtract 0 from 7, we get 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Going ahead to step 7:
If we divide 70 by 21, we get 3 and a remainder of 7.
The next digit of our result is 3. 
Result so far: 31860.3
The remainder is 7 after subtracting 63 from 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Going ahead to step 8:
When dividing 70 by 21, we get 3 with a remainder of 7.
The number 3 becomes the next digit in our result. 
Result so far: 31860.33
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.

The quotient of the division is 31860.33, and the remainder is 0.007.