We look at the division of 870889 by 91 
The aim is to understand the frequency of 91 in 870889.

Let's proceed to step 1:
91 can be fit into 8 0 times, resulting in a remainder of 8.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 8 leaves us with 8.
Grab the next digit (7) from the dividend, add it to 8, then carry on: 87 / 91

On to step 2:
91 goes into 87 0 times with a remainder of 87.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 87 and we're left with 87.
Take the next digit (0) from the dividend and append it to 87, then repeat: 870 / 91

Moving on to step 3:
91 can be fit into 870 9 times, resulting in a remainder of 51.
Write down 9 as next digit of the result. 
Result so far: 9.0
Subtract 819 from 870 to get 51.
Grab the next digit (8) from the dividend, add it to 51, then carry on: 518 / 91

On to step 4:
If we divide 518 by 91, we get 5 and a remainder of 63.
Put 5 as the next digit of the answer. 
Result so far: 95.0
If we subtract 455 from 518, we get 63.
Append the next digit (8) from the dividend to 63 and continue with: 638 / 91

Going ahead to step 5:
638 divided by 91 is 7 with a remainder of 1.
The number 7 becomes the next digit in our result. 
Result so far: 957.0
Subtracting 637 from 638 leaves us with 1.
Take the next digit (9) from the dividend and append it to 1, then repeat: 19 / 91

Going ahead to step 6:
The number 91 fits into 19 0 times, leaving a remainder of 19.
The number 0 becomes the next digit in our result. 
Result so far: 9570.0
If we subtract 0 from 19, we get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Step 7:
When dividing 190 by 91, we get 2 with a remainder of 8.
Record the quotient 2 as the next digit in the result. 
Result so far: 9570.2
Deduct 182 from 190 and we're left 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.

Step 8:
The number 91 fits into 80 0 times, leaving a remainder of 80.
Write down 0 as next digit of the result. 
Result so far: 9570.2
If we subtract 0 from 80, we get 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

Step 9:
When dividing 800 by 91, we get 8 with a remainder of 72.
The next digit of our result is 8. 
Result so far: 9570.208
Subtracting 728 from 800 leaves us with 72.
Since there are no more digits in the dividend, we add a zero to the remainder making it 720, and continue the process.

Moving on to step 10:
When dividing 720 by 91, we get 7 with a remainder of 83.
Put 7 as the next digit of the answer. 
Result so far: 9570.2087
If we take 637 away from 720, we end up with 83.
Since there are no more digits in the dividend, we add a zero to the remainder making it 830, and continue the process.

On to step 11:
If we divide 830 by 91, we get 9 and a remainder of 11.
Record the quotient 9 as the next digit in the result. 
Result so far: 9570.20879
If we take 819 away from 830, 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.

Step 12:
110 divided by 91 is 1 with a remainder of 19.
Put 1 as the next digit of the answer. 
Result so far: 9570.208791
If we subtract 91 from 110, we get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Step 13:
91 goes into 190 2 times with a remainder of 8.
Write down 2 as next digit of the result. 
Result so far: 9570.2087912
The remainder is 8 after subtracting 182 from 190.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Moving on to step 14:
When dividing 80 by 91, we get 0 with a remainder of 80.
Use 0 as the next digit of our solution. 
Result so far: 9570.2087912
Subtracting 0 from 80 leaves us with 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

In conclusion, the division gives 9570.2087912 with a balance of 8e-08.