866981 divided by 91 
The aim is to understand the frequency of 91 in 866981.

Going ahead to step 1:
The number 91 fits into 8 0 times, leaving a remainder of 8.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 8 leaves us with 8.
Take the next digit (6) from the dividend and append it to 8, then repeat: 86 / 91

Let's proceed to step 2:
91 goes into 86 0 times with a remainder of 86.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 86, we get 86.
Append the next digit (6) from the dividend to 86 and continue with: 866 / 91

On to step 3:
91 goes into 866 9 times with a remainder of 47.
Record the quotient 9 as the next digit in the result. 
Result so far: 9.0
Subtract 819 from 866 to get 47.
Append the next digit (9) from the dividend to 47 and continue with: 479 / 91

Step 4:
When dividing 479 by 91, we get 5 with a remainder of 24.
Record the quotient 5 as the next digit in the result. 
Result so far: 95.0
Deduct 455 from 479 and we're left with 24.
Fetch the next digit (8) from the dividend, attach it to 24 and continue: 248 / 91

Advancing to step 5:
91 goes into 248 2 times with a remainder of 66.
Write down 2 as next digit of the result. 
Result so far: 952.0
Subtract 182 from 248 to get 66.
Grab the next digit (1) from the dividend, add it to 66, then carry on: 661 / 91

On to step 6:
When dividing 661 by 91, we get 7 with a remainder of 24.
The next digit of our result is 7. 
Result so far: 9527.0
If we subtract 637 from 661, we get 24.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

Going ahead to step 7:
91 can be fit into 240 2 times, resulting in a remainder of 58.
Use 2 as the next digit of our solution. 
Result so far: 9527.2
Subtracting 182 from 240 leaves us with 58.
Since there are no more digits in the dividend, we add a zero to the remainder making it 580, and continue the process.

Advancing to step 8:
When dividing 580 by 91, we get 6 with a remainder of 34.
The number 6 becomes the next digit in our result. 
Result so far: 9527.26
If we take 546 away from 580, we end up with 34.
Since there are no more digits in the dividend, we add a zero to the remainder making it 340, and continue the process.

Advancing to step 9:
340 divided by 91 is 3 with a remainder of 67.
The number 3 becomes the next digit in our result. 
Result so far: 9527.263
If we subtract 273 from 340, we get 67.
Since there are no more digits in the dividend, we add a zero to the remainder making it 670, and continue the process.

Advancing to step 10:
The number 91 fits into 670 7 times, leaving a remainder of 33.
Use 7 as the next digit of our solution. 
Result so far: 9527.2637
Deduct 637 from 670 and we're left with 33.
Since there are no more digits in the dividend, we add a zero to the remainder making it 330, and continue the process.

Let's proceed to step 11:
When dividing 330 by 91, we get 3 with a remainder of 57.
Write down 3 as next digit of the result. 
Result so far: 9527.26373
If we subtract 273 from 330, we get 57.
Since there are no more digits in the dividend, we add a zero to the remainder making it 570, and continue the process.

On to step 12:
The number 91 fits into 570 6 times, leaving a remainder of 24.
The number 6 becomes the next digit in our result. 
Result so far: 9527.263736
If we subtract 546 from 570, we get 24.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

Step 13:
91 can be fit into 240 2 times, resulting in a remainder of 58.
The next digit of our result is 2. 
Result so far: 9527.2637362
If we subtract 182 from 240, we get 58.
Since there are no more digits in the dividend, we add a zero to the remainder making it 580, and continue the process.

Going ahead to step 14:
The number 91 fits into 580 6 times, leaving a remainder of 34.
Use 6 as the next digit of our solution. 
Result so far: 9527.26373626
Deduct 546 from 580 and we're left with 34.
Since there are no more digits in the dividend, we add a zero to the remainder making it 340, and continue the process.

The final outcome is 9527.26373626, with a leftover of 3.4e-08.