We look at the division of 71001 by 91 
The aim is to understand the frequency of 91 in 71001.

Advancing to step 1:
When dividing 7 by 91, we get 0 with a remainder of 7.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 7 leaves us with 7.
Take the next digit (1) from the dividend and append it to 7, then repeat: 71 / 91

On to step 2:
The number 91 fits into 71 0 times, leaving a remainder of 71.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Deduct 0 from 71 and we're left with 71.
Include the next digit (0) from the dividend after 71, then repeat: 710 / 91

Moving on to step 3:
91 goes into 710 7 times with a remainder of 73.
The number 7 becomes the next digit in our result. 
Result so far: 7.0
Deduct 637 from 710 and we're left with 73.
Take the next digit (0) from the dividend and append it to 73, then repeat: 730 / 91

Advancing to step 4:
730 divided by 91 is 8 with a remainder of 2.
The number 8 becomes the next digit in our result. 
Result so far: 78.0
The remainder is 2 after subtracting 728 from 730.
Append the next digit (1) from the dividend to 2 and continue with: 21 / 91

Advancing to step 5:
If we divide 21 by 91, we get 0 and a remainder of 21.
Write down 0 as next digit of the result. 
Result so far: 780.0
If we subtract 0 from 21, we get 21.
Since there are no more digits in the dividend, we add a zero to the remainder making it 210, and continue the process.

Moving on to step 6:
When dividing 210 by 91, we get 2 with a remainder of 28.
Put 2 as the next digit of the answer. 
Result so far: 780.2
Subtracting 182 from 210 leaves us with 28.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

Advancing to step 7:
91 can be fit into 280 3 times, resulting in a remainder of 7.
Use 3 as the next digit of our solution. 
Result so far: 780.23
Subtracting 273 from 280 leaves us 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.

Step 8:
70 divided by 91 is 0 with a remainder of 70.
Put 0 as the next digit of the answer. 
Result so far: 780.23
The remainder is 70 after subtracting 0 from 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

On to step 9:
700 divided by 91 is 7 with a remainder of 63.
Use 7 as the next digit of our solution. 
Result so far: 780.2307
If we take 637 away from 700, we end up with 63.
Since there are no more digits in the dividend, we add a zero to the remainder making it 630, and continue the process.

Advancing to step 10:
91 can be fit into 630 6 times, resulting in a remainder of 84.
The next digit of our result is 6. 
Result so far: 780.23076
Subtracting 546 from 630 leaves us with 84.
Since there are no more digits in the dividend, we add a zero to the remainder making it 840, and continue the process.

Going ahead to step 11:
If we divide 840 by 91, we get 9 and a remainder of 21.
Put 9 as the next digit of the answer. 
Result so far: 780.230769
Deduct 819 from 840 and we're left with 21.
Since there are no more digits in the dividend, we add a zero to the remainder making it 210, and continue the process.

On to step 12:
When dividing 210 by 91, we get 2 with a remainder of 28.
Record the quotient 2 as the next digit in the result. 
Result so far: 780.2307692
If we subtract 182 from 210, we get 28.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

Going ahead to step 13:
91 goes into 280 3 times with a remainder of 7.
Use 3 as the next digit of our solution. 
Result so far: 780.23076923
Subtracting 273 from 280 leaves us 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.

After the division, we end up with 780.23076923 and a remainder of 7e-09.