We look at the division of 21091 by 11 
The aim is to understand the frequency of 11 in 21091.

Step 1:
2 divided by 11 is 0 with a remainder of 2.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 2 and we're left with 2.
Append the next digit (1) from the dividend to 2 and continue with: 21 / 11

Step 2:
11 goes into 21 1 times with a remainder of 10.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Deduct 11 from 21 and we're left with 10.
Fetch the next digit (0) from the dividend, attach it to 10 and continue: 100 / 11

Going ahead to step 3:
11 can be fit into 100 9 times, resulting in a remainder of 1.
The number 9 becomes the next digit in our result. 
Result so far: 19.0
If we subtract 99 from 100, we get 1.
Grab the next digit (9) from the dividend, add it to 1, then carry on: 19 / 11

Going ahead to step 4:
19 divided by 11 is 1 with a remainder of 8.
Record the quotient 1 as the next digit in the result. 
Result so far: 191.0
The remainder is 8 after subtracting 11 from 19.
Include the next digit (1) from the dividend after 8, then repeat: 81 / 11

On to step 5:
81 divided by 11 is 7 with a remainder of 4.
Use 7 as the next digit of our solution. 
Result so far: 1917.0
If we subtract 77 from 81, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Step 6:
The number 11 fits into 40 3 times, leaving a remainder of 7.
Write down 3 as next digit of the result. 
Result so far: 1917.3
If we subtract 33 from 40, 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:
When dividing 70 by 11, we get 6 with a remainder of 4.
Record the quotient 6 as the next digit in the result. 
Result so far: 1917.36
Subtracting 66 from 70 leaves us with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Going ahead to step 8:
When dividing 40 by 11, we get 3 with a remainder of 7.
Put 3 as the next digit of the answer. 
Result so far: 1917.363
Subtract 33 from 40 to 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.

Let's proceed to step 9:
The number 11 fits into 70 6 times, leaving a remainder of 4.
The next digit of our result is 6. 
Result so far: 1917.3636
If we take 66 away from 70, we end up with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Advancing to step 10:
If we divide 40 by 11, we get 3 and a remainder of 7.
The next digit of our result is 3. 
Result so far: 1917.36363
If we subtract 33 from 40, 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 11:
11 can be fit into 70 6 times, resulting in a remainder of 4.
Put 6 as the next digit of the answer. 
Result so far: 1917.363636
If we subtract 66 from 70, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Let's proceed to step 12:
If we divide 40 by 11, we get 3 and a remainder of 7.
Use 3 as the next digit of our solution. 
Result so far: 1917.3636363
Subtract 33 from 40 to 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.

Step 13:
The number 11 fits into 70 6 times, leaving a remainder of 4.
Put 6 as the next digit of the answer. 
Result so far: 1917.36363636
The remainder is 4 after subtracting 66 from 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

In conclusion, the division gives 1917.36363636 with a balance of 4e-09.