We look at the division of 536415 by 91 
The aim is to understand the frequency of 91 in 536415.

Let's proceed to step 1:
The number 91 fits into 5 0 times, leaving a remainder of 5.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 5 and we're left with 5.
Fetch the next digit (3) from the dividend, attach it to 5 and continue: 53 / 91

On to step 2:
When dividing 53 by 91, we get 0 with a remainder of 53.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 53 and we're left with 53.
Append the next digit (6) from the dividend to 53 and continue with: 536 / 91

Advancing to step 3:
When dividing 536 by 91, we get 5 with a remainder of 81.
The next digit of our result is 5. 
Result so far: 5.0
If we subtract 455 from 536, we get 81.
Fetch the next digit (4) from the dividend, attach it to 81 and continue: 814 / 91

Advancing to step 4:
91 can be fit into 814 8 times, resulting in a remainder of 86.
The next digit of our result is 8. 
Result so far: 58.0
If we subtract 728 from 814, we get 86.
Bring next digit (1) of the dividend behind the 86 and repeat the process: 861 / 91

Going ahead to step 5:
When dividing 861 by 91, we get 9 with a remainder of 42.
The number 9 becomes the next digit in our result. 
Result so far: 589.0
Deduct 819 from 861 and we're left with 42.
Grab the next digit (5) from the dividend, add it to 42, then carry on: 425 / 91

Let's proceed to step 6:
The number 91 fits into 425 4 times, leaving a remainder of 61.
Write down 4 as next digit of the result. 
Result so far: 5894.0
If we take 364 away from 425, we end up 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.

Moving on to step 7:
If we divide 610 by 91, we get 6 and a remainder of 64.
The next digit of our result is 6. 
Result so far: 5894.6
Subtracting 546 from 610 leaves us 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.

On to step 8:
The number 91 fits into 640 7 times, leaving a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 5894.67
If we take 637 away from 640, we end up 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.

Moving on to step 9:
91 goes into 30 0 times with a remainder of 30.
Put 0 as the next digit of the answer. 
Result so far: 5894.67
Deduct 0 from 30 and we're left with 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.
The next digit of our result is 3. 
Result so far: 5894.6703
Deduct 273 from 300 and we're left with 27.
Since there are no more digits in the dividend, we add a zero to the remainder making it 270, and continue the process.

Step 11:
91 goes into 270 2 times with a remainder of 88.
The number 2 becomes the next digit in our result. 
Result so far: 5894.67032
If we subtract 182 from 270, we get 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:
91 goes into 880 9 times with a remainder of 61.
Record the quotient 9 as the next digit in the result. 
Result so far: 5894.670329
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.

Let's proceed to step 13:
610 divided by 91 is 6 with a remainder of 64.
Write down 6 as next digit of the result. 
Result so far: 5894.6703296
If we subtract 546 from 610, we 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.
Write down 7 as next digit of the result. 
Result so far: 5894.67032967
If we subtract 637 from 640, we get 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 outcome is 5894.67032967, with a leftover of 3e-09.