We're dividing 1439 by 91 
The aim is to understand the frequency of 91 in 1439.

Step 1:
The number 91 fits into 1 0 times, leaving a remainder of 1.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 1 after subtracting 0 from 1.
Append the next digit (4) from the dividend to 1 and continue with: 14 / 91

Step 2:
91 can be fit into 14 0 times, resulting in a remainder of 14.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 14, we get 14.
Include the next digit (3) from the dividend after 14, then repeat: 143 / 91

Advancing to step 3:
The number 91 fits into 143 1 times, leaving a remainder of 52.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Subtracting 91 from 143 leaves us with 52.
Grab the next digit (9) from the dividend, add it to 52, then carry on: 529 / 91

Let's proceed to step 4:
The number 91 fits into 529 5 times, leaving a remainder of 74.
The number 5 becomes the next digit in our result. 
Result so far: 15.0
The remainder is 74 after subtracting 455 from 529.
Since there are no more digits in the dividend, we add a zero to the remainder making it 740, and continue the process.

On to step 5:
91 goes into 740 8 times with a remainder of 12.
Use 8 as the next digit of our solution. 
Result so far: 15.8
If we subtract 728 from 740, we get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Advancing to step 6:
120 divided by 91 is 1 with a remainder of 29.
The next digit of our result is 1. 
Result so far: 15.81
Deduct 91 from 120 and we're left with 29.
Since there are no more digits in the dividend, we add a zero to the remainder making it 290, and continue the process.

On to step 7:
If we divide 290 by 91, we get 3 and a remainder of 17.
Put 3 as the next digit of the answer. 
Result so far: 15.813
The remainder is 17 after subtracting 273 from 290.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Going ahead to step 8:
The number 91 fits into 170 1 times, leaving a remainder of 79.
Record the quotient 1 as the next digit in the result. 
Result so far: 15.8131
Deduct 91 from 170 and we're left with 79.
Since there are no more digits in the dividend, we add a zero to the remainder making it 790, and continue the process.

Going ahead to step 9:
790 divided by 91 is 8 with a remainder of 62.
The next digit of our result is 8. 
Result so far: 15.81318
Subtract 728 from 790 to get 62.
Since there are no more digits in the dividend, we add a zero to the remainder making it 620, and continue the process.

Going ahead to step 10:
The number 91 fits into 620 6 times, leaving a remainder of 74.
Put 6 as the next digit of the answer. 
Result so far: 15.813186
Subtract 546 from 620 to get 74.
Since there are no more digits in the dividend, we add a zero to the remainder making it 740, and continue the process.

Advancing to step 11:
If we divide 740 by 91, we get 8 and a remainder of 12.
The number 8 becomes the next digit in our result. 
Result so far: 15.8131868
If we take 728 away from 740, we end up with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Let's proceed to step 12:
When dividing 120 by 91, we get 1 with a remainder of 29.
Use 1 as the next digit of our solution. 
Result so far: 15.81318681
If we subtract 91 from 120, we get 29.
Since there are no more digits in the dividend, we add a zero to the remainder making it 290, and continue the process.

Our division results in 15.81318681 with a remaining 2.9e-08.