721913 divided by 91 
The aim is to understand the frequency of 91 in 721913.

Advancing to step 1:
91 goes into 7 0 times with a remainder of 7.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 7 and we're left with 7.
Include the next digit (2) from the dividend after 7, then repeat: 72 / 91

Moving on to step 2:
91 can be fit into 72 0 times, resulting in a remainder of 72.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 72 after subtracting 0 from 72.
Include the next digit (1) from the dividend after 72, then repeat: 721 / 91

Going ahead to step 3:
When dividing 721 by 91, we get 7 with a remainder of 84.
Use 7 as the next digit of our solution. 
Result so far: 7.0
Deduct 637 from 721 and we're left with 84.
Bring next digit (9) of the dividend behind the 84 and repeat the process: 849 / 91

Advancing to step 4:
When dividing 849 by 91, we get 9 with a remainder of 30.
The number 9 becomes the next digit in our result. 
Result so far: 79.0
If we take 819 away from 849, we end up with 30.
Append the next digit (1) from the dividend to 30 and continue with: 301 / 91

Moving on to step 5:
When dividing 301 by 91, we get 3 with a remainder of 28.
Write down 3 as next digit of the result. 
Result so far: 793.0
Subtract 273 from 301 to get 28.
Grab the next digit (3) from the dividend, add it to 28, then carry on: 283 / 91

Going ahead to step 6:
91 can be fit into 283 3 times, resulting in a remainder of 10.
Put 3 as the next digit of the answer. 
Result so far: 7933.0
If we take 273 away from 283, we end up with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Moving on to step 7:
91 can be fit into 100 1 times, resulting in a remainder of 9.
Use 1 as the next digit of our solution. 
Result so far: 7933.1
Subtract 91 from 100 to get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Step 8:
When dividing 90 by 91, we get 0 with a remainder of 90.
The next digit of our result is 0. 
Result so far: 7933.1
The remainder is 90 after subtracting 0 from 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 900, and continue the process.

Moving on to step 9:
The number 91 fits into 900 9 times, leaving a remainder of 81.
Use 9 as the next digit of our solution. 
Result so far: 7933.109
Subtract 819 from 900 to get 81.
Since there are no more digits in the dividend, we add a zero to the remainder making it 810, and continue the process.

Let's proceed to step 10:
The number 91 fits into 810 8 times, leaving a remainder of 82.
Record the quotient 8 as the next digit in the result. 
Result so far: 7933.1098
Deduct 728 from 810 and we're left with 82.
Since there are no more digits in the dividend, we add a zero to the remainder making it 820, and continue the process.

On to step 11:
91 can be fit into 820 9 times, resulting in a remainder of 1.
Record the quotient 9 as the next digit in the result. 
Result so far: 7933.10989
The remainder is 1 after subtracting 819 from 820.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Moving on to step 12:
91 can be fit into 10 0 times, resulting in a remainder of 10.
The number 0 becomes the next digit in our result. 
Result so far: 7933.10989
Deduct 0 from 10 and we're left with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 13:
91 can be fit into 100 1 times, resulting in a remainder of 9.
Record the quotient 1 as the next digit in the result. 
Result so far: 7933.1098901
If we take 91 away from 100, we end up with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Step 14:
91 goes into 90 0 times with a remainder of 90.
The next digit of our result is 0. 
Result so far: 7933.1098901
The remainder is 90 after subtracting 0 from 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 900, and continue the process.

In conclusion, the division gives 7933.1098901 with a balance of 9e-08.