81691473 divided by 13 
The aim is to understand the frequency of 13 in 81691473.

Advancing to step 1:
13 goes into 8 0 times with a remainder of 8.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 8, we end up with 8.
Take the next digit (1) from the dividend and append it to 8, then repeat: 81 / 13

On to step 2:
If we divide 81 by 13, we get 6 and a remainder of 3.
Put 6 as the next digit of the answer. 
Result so far: 6.0
If we take 78 away from 81, we end up with 3.
Take the next digit (6) from the dividend and append it to 3, then repeat: 36 / 13

Step 3:
13 goes into 36 2 times with a remainder of 10.
Use 2 as the next digit of our solution. 
Result so far: 62.0
If we take 26 away from 36, we end up with 10.
Take the next digit (9) from the dividend and append it to 10, then repeat: 109 / 13

Going ahead to step 4:
The number 13 fits into 109 8 times, leaving a remainder of 5.
Record the quotient 8 as the next digit in the result. 
Result so far: 628.0
If we take 104 away from 109, we end up with 5.
Take the next digit (1) from the dividend and append it to 5, then repeat: 51 / 13

On to step 5:
The number 13 fits into 51 3 times, leaving a remainder of 12.
Write down 3 as next digit of the result. 
Result so far: 6283.0
Subtracting 39 from 51 leaves us with 12.
Bring next digit (4) of the dividend behind the 12 and repeat the process: 124 / 13

On to step 6:
If we divide 124 by 13, we get 9 and a remainder of 7.
Write down 9 as next digit of the result. 
Result so far: 62839.0
Subtracting 117 from 124 leaves us with 7.
Append the next digit (7) from the dividend to 7 and continue with: 77 / 13

On to step 7:
13 can be fit into 77 5 times, resulting in a remainder of 12.
The next digit of our result is 5. 
Result so far: 628395.0
If we take 65 away from 77, we end up with 12.
Take the next digit (3) from the dividend and append it to 12, then repeat: 123 / 13

Going ahead to step 8:
13 can be fit into 123 9 times, resulting in a remainder of 6.
Use 9 as the next digit of our solution. 
Result so far: 6283959.0
If we take 117 away from 123, we end up with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Let's proceed to step 9:
13 goes into 60 4 times with a remainder of 8.
Use 4 as the next digit of our solution. 
Result so far: 6283959.4
Deduct 52 from 60 and we're left with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Advancing to step 10:
13 can be fit into 80 6 times, resulting in a remainder of 2.
Write down 6 as next digit of the result. 
Result so far: 6283959.46
Deduct 78 from 80 and we're left with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Let's proceed to step 11:
If we divide 20 by 13, we get 1 and a remainder of 7.
Put 1 as the next digit of the answer. 
Result so far: 6283959.461
If we take 13 away from 20, we end up 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 12:
The number 13 fits into 70 5 times, leaving a remainder of 5.
Record the quotient 5 as the next digit in the result. 
Result so far: 6283959.4615
If we subtract 65 from 70, we get 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Advancing to step 13:
13 can be fit into 50 3 times, resulting in a remainder of 11.
Use 3 as the next digit of our solution. 
Result so far: 6283959.46153
If we take 39 away from 50, we end up with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

On to step 14:
The number 13 fits into 110 8 times, leaving a remainder of 6.
The number 8 becomes the next digit in our result. 
Result so far: 6283959.461538
The remainder is 6 after subtracting 104 from 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Advancing to step 15:
60 divided by 13 is 4 with a remainder of 8.
Record the quotient 4 as the next digit in the result. 
Result so far: 6283959.4615384
Subtracting 52 from 60 leaves us with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Moving on to step 16:
When dividing 80 by 13, we get 6 with a remainder of 2.
The next digit of our result is 6. 
Result so far: 6283959.46153846
The remainder is 2 after subtracting 78 from 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Our division results in 6283959.46153846 with a remaining 2e-09.