745639 ÷ 81 
The aim is to understand the frequency of 81 in 745639.

Moving on to step 1:
When dividing 7 by 81, we get 0 with a remainder of 7.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 7, we end up with 7.
Take the next digit (4) from the dividend and append it to 7, then repeat: 74 / 81

Step 2:
74 divided by 81 is 0 with a remainder of 74.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 74 to get 74.
Bring next digit (5) of the dividend behind the 74 and repeat the process: 745 / 81

Step 3:
The number 81 fits into 745 9 times, leaving a remainder of 16.
The number 9 becomes the next digit in our result. 
Result so far: 9.0
Deduct 729 from 745 and we're left with 16.
Grab the next digit (6) from the dividend, add it to 16, then carry on: 166 / 81

On to step 4:
The number 81 fits into 166 2 times, leaving a remainder of 4.
Use 2 as the next digit of our solution. 
Result so far: 92.0
Subtracting 162 from 166 leaves us with 4.
Fetch the next digit (3) from the dividend, attach it to 4 and continue: 43 / 81

Moving on to step 5:
When dividing 43 by 81, we get 0 with a remainder of 43.
Record the quotient 0 as the next digit in the result. 
Result so far: 920.0
If we take 0 away from 43, we end up with 43.
Fetch the next digit (9) from the dividend, attach it to 43 and continue: 439 / 81

Going ahead to step 6:
If we divide 439 by 81, we get 5 and a remainder of 34.
Use 5 as the next digit of our solution. 
Result so far: 9205.0
If we subtract 405 from 439, we get 34.
Since there are no more digits in the dividend, we add a zero to the remainder making it 340, and continue the process.

Advancing to step 7:
81 can be fit into 340 4 times, resulting in a remainder of 16.
Record the quotient 4 as the next digit in the result. 
Result so far: 9205.4
If we take 324 away from 340, we end up with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Advancing to step 8:
81 goes into 160 1 times with a remainder of 79.
Put 1 as the next digit of the answer. 
Result so far: 9205.41
The remainder is 79 after subtracting 81 from 160.
Since there are no more digits in the dividend, we add a zero to the remainder making it 790, and continue the process.

On to step 9:
The number 81 fits into 790 9 times, leaving a remainder of 61.
Record the quotient 9 as the next digit in the result. 
Result so far: 9205.419
Subtracting 729 from 790 leaves us 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 10:
If we divide 610 by 81, we get 7 and a remainder of 43.
Record the quotient 7 as the next digit in the result. 
Result so far: 9205.4197
Subtract 567 from 610 to get 43.
Since there are no more digits in the dividend, we add a zero to the remainder making it 430, and continue the process.

Going ahead to step 11:
When dividing 430 by 81, we get 5 with a remainder of 25.
Use 5 as the next digit of our solution. 
Result so far: 9205.41975
Subtracting 405 from 430 leaves us with 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

Let's proceed to step 12:
The number 81 fits into 250 3 times, leaving a remainder of 7.
Write down 3 as next digit of the result. 
Result so far: 9205.419753
Deduct 243 from 250 and we're left 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.

Going ahead to step 13:
If we divide 70 by 81, we get 0 and a remainder of 70.
Use 0 as the next digit of our solution. 
Result so far: 9205.419753
If we subtract 0 from 70, we get 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

Moving on to step 14:
The number 81 fits into 700 8 times, leaving a remainder of 52.
Record the quotient 8 as the next digit in the result. 
Result so far: 9205.41975308
Subtracting 648 from 700 leaves us with 52.
Since there are no more digits in the dividend, we add a zero to the remainder making it 520, and continue the process.

The final result is 9205.41975308 with a remainder of 5.2e-08.