123639 ÷ 91 
The aim is to understand the frequency of 91 in 123639.

On to step 1:
91 can be fit into 1 0 times, resulting in a remainder of 1.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 1, we get 1.
Take the next digit (2) from the dividend and append it to 1, then repeat: 12 / 91

Going ahead to step 2:
91 goes into 12 0 times with a remainder of 12.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 12 leaves us with 12.
Fetch the next digit (3) from the dividend, attach it to 12 and continue: 123 / 91

Going ahead to step 3:
The number 91 fits into 123 1 times, leaving a remainder of 32.
Write down 1 as next digit of the result. 
Result so far: 1.0
If we take 91 away from 123, we end up with 32.
Fetch the next digit (6) from the dividend, attach it to 32 and continue: 326 / 91

On to step 4:
326 divided by 91 is 3 with a remainder of 53.
Put 3 as the next digit of the answer. 
Result so far: 13.0
Deduct 273 from 326 and we're left with 53.
Fetch the next digit (3) from the dividend, attach it to 53 and continue: 533 / 91

On to step 5:
91 can be fit into 533 5 times, resulting in a remainder of 78.
Put 5 as the next digit of the answer. 
Result so far: 135.0
Deduct 455 from 533 and we're left with 78.
Include the next digit (9) from the dividend after 78, then repeat: 789 / 91

Going ahead to step 6:
The number 91 fits into 789 8 times, leaving a remainder of 61.
The next digit of our result is 8. 
Result so far: 1358.0
Deduct 728 from 789 and we're left with 61.
Since there are no more digits in the dividend, we add a zero to the remainder making it 610, and continue the process.

Going ahead to step 7:
91 goes into 610 6 times with a remainder of 64.
Put 6 as the next digit of the answer. 
Result so far: 1358.6
If we take 546 away from 610, we end up with 64.
Since there are no more digits in the dividend, we add a zero to the remainder making it 640, and continue the process.

Step 8:
640 divided by 91 is 7 with a remainder of 3.
Write down 7 as next digit of the result. 
Result so far: 1358.67
Deduct 637 from 640 and we're left with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Going ahead to step 9:
30 divided by 91 is 0 with a remainder of 30.
The number 0 becomes the next digit in our result. 
Result so far: 1358.67
The remainder is 30 after subtracting 0 from 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Moving on to step 10:
91 goes into 300 3 times with a remainder of 27.
Put 3 as the next digit of the answer. 
Result so far: 1358.6703
The remainder is 27 after subtracting 273 from 300.
Since there are no more digits in the dividend, we add a zero to the remainder making it 270, and continue the process.

Going ahead to step 11:
The number 91 fits into 270 2 times, leaving a remainder of 88.
Record the quotient 2 as the next digit in the result. 
Result so far: 1358.67032
If we take 182 away from 270, we end up with 88.
Since there are no more digits in the dividend, we add a zero to the remainder making it 880, and continue the process.

Advancing to step 12:
When dividing 880 by 91, we get 9 with a remainder of 61.
Put 9 as the next digit of the answer. 
Result so far: 1358.670329
Deduct 819 from 880 and we're left with 61.
Since there are no more digits in the dividend, we add a zero to the remainder making it 610, and continue the process.

Step 13:
If we divide 610 by 91, we get 6 and a remainder of 64.
Use 6 as the next digit of our solution. 
Result so far: 1358.6703296
Subtract 546 from 610 to get 64.
Since there are no more digits in the dividend, we add a zero to the remainder making it 640, and continue the process.

Advancing to step 14:
91 goes into 640 7 times with a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 1358.67032967
Subtracting 637 from 640 leaves us with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

The final result is 1358.67032967 with a remainder of 3e-09.