Let's divide 655790 by 21
The aim is to understand the frequency of 21 in 655790.

On to step 1:
The number 21 fits into 6 0 times, leaving a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Fetch the next digit (5) from the dividend, attach it to 6 and continue: 65 / 21

Going ahead to step 2:
The number 21 fits into 65 3 times, leaving a remainder of 2.
Record the quotient 3 as the next digit in the result. 
Result so far: 3.0
Subtract 63 from 65 to get 2.
Append the next digit (5) from the dividend to 2 and continue with: 25 / 21

Going ahead to step 3:
21 goes into 25 1 times with a remainder of 4.
Put 1 as the next digit of the answer. 
Result so far: 31.0
The remainder is 4 after subtracting 21 from 25.
Take the next digit (7) from the dividend and append it to 4, then repeat: 47 / 21

Let's proceed to step 4:
21 goes into 47 2 times with a remainder of 5.
The number 2 becomes the next digit in our result. 
Result so far: 312.0
Subtracting 42 from 47 leaves us with 5.
Bring next digit (9) of the dividend behind the 5 and repeat the process: 59 / 21

Step 5:
The number 21 fits into 59 2 times, leaving a remainder of 17.
Put 2 as the next digit of the answer. 
Result so far: 3122.0
If we subtract 42 from 59, we get 17.
Grab the next digit (0) from the dividend, add it to 17, then carry on: 170 / 21

Let's proceed to step 6:
170 divided by 21 is 8 with a remainder of 2.
The number 8 becomes the next digit in our result. 
Result so far: 31228.0
If we subtract 168 from 170, we get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Step 7:
If we divide 20 by 21, we get 0 and a remainder of 20.
The number 0 becomes the next digit in our result. 
Result so far: 31228.0
The remainder is 20 after subtracting 0 from 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Moving on to step 8:
If we divide 200 by 21, we get 9 and a remainder of 11.
Put 9 as the next digit of the answer. 
Result so far: 31228.09
If we take 189 away from 200, we end up with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Let's proceed to step 9:
If we divide 110 by 21, we get 5 and a remainder of 5.
Put 5 as the next digit of the answer. 
Result so far: 31228.095
Deduct 105 from 110 and we're left 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.

Going ahead to step 10:
If we divide 50 by 21, we get 2 and a remainder of 8.
Use 2 as the next digit of our solution. 
Result so far: 31228.0952
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 11:
21 goes into 80 3 times with a remainder of 17.
Use 3 as the next digit of our solution. 
Result so far: 31228.09523
If we subtract 63 from 80, we get 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 12:
21 goes into 170 8 times with a remainder of 2.
Use 8 as the next digit of our solution. 
Result so far: 31228.095238
Subtract 168 from 170 to get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Let's proceed to step 13:
21 can be fit into 20 0 times, resulting in a remainder of 20.
The number 0 becomes the next digit in our result. 
Result so far: 31228.095238
Deduct 0 from 20 and we're left 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.

On to step 14:
The number 21 fits into 200 9 times, leaving a remainder of 11.
Write down 9 as next digit of the result. 
Result so far: 31228.09523809
Subtract 189 from 200 to get 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

The final result is 31228.09523809 with a remainder of 1.1e-08.