Let's divide 644583 by 81
The aim is to understand the frequency of 81 in 644583.

Moving on to step 1:
6 divided by 81 is 0 with a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Deduct 0 from 6 and we're left with 6.
Fetch the next digit (4) from the dividend, attach it to 6 and continue: 64 / 81

Moving on to step 2:
When dividing 64 by 81, we get 0 with a remainder of 64.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 64, we get 64.
Take the next digit (4) from the dividend and append it to 64, then repeat: 644 / 81

Going ahead to step 3:
81 can be fit into 644 7 times, resulting in a remainder of 77.
Record the quotient 7 as the next digit in the result. 
Result so far: 7.0
Deduct 567 from 644 and we're left with 77.
Fetch the next digit (5) from the dividend, attach it to 77 and continue: 775 / 81

Moving on to step 4:
If we divide 775 by 81, we get 9 and a remainder of 46.
Record the quotient 9 as the next digit in the result. 
Result so far: 79.0
Subtract 729 from 775 to get 46.
Include the next digit (8) from the dividend after 46, then repeat: 468 / 81

Let's proceed to step 5:
468 divided by 81 is 5 with a remainder of 63.
Write down 5 as next digit of the result. 
Result so far: 795.0
The remainder is 63 after subtracting 405 from 468.
Append the next digit (3) from the dividend to 63 and continue with: 633 / 81

Moving on to step 6:
81 can be fit into 633 7 times, resulting in a remainder of 66.
Use 7 as the next digit of our solution. 
Result so far: 7957.0
If we subtract 567 from 633, we get 66.
Since there are no more digits in the dividend, we add a zero to the remainder making it 660, and continue the process.

On to step 7:
The number 81 fits into 660 8 times, leaving a remainder of 12.
Put 8 as the next digit of the answer. 
Result so far: 7957.8
Deduct 648 from 660 and we're left 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.

Step 8:
120 divided by 81 is 1 with a remainder of 39.
The next digit of our result is 1. 
Result so far: 7957.81
Deduct 81 from 120 and we're left with 39.
Since there are no more digits in the dividend, we add a zero to the remainder making it 390, and continue the process.

Step 9:
If we divide 390 by 81, we get 4 and a remainder of 66.
Put 4 as the next digit of the answer. 
Result so far: 7957.814
Deduct 324 from 390 and we're left with 66.
Since there are no more digits in the dividend, we add a zero to the remainder making it 660, and continue the process.

Advancing to step 10:
The number 81 fits into 660 8 times, leaving a remainder of 12.
Record the quotient 8 as the next digit in the result. 
Result so far: 7957.8148
Deduct 648 from 660 and we're left 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.

Going ahead to step 11:
The number 81 fits into 120 1 times, leaving a remainder of 39.
The number 1 becomes the next digit in our result. 
Result so far: 7957.81481
If we subtract 81 from 120, we get 39.
Since there are no more digits in the dividend, we add a zero to the remainder making it 390, and continue the process.

Advancing to step 12:
81 goes into 390 4 times with a remainder of 66.
Use 4 as the next digit of our solution. 
Result so far: 7957.814814
Subtracting 324 from 390 leaves us with 66.
Since there are no more digits in the dividend, we add a zero to the remainder making it 660, and continue the process.

Let's proceed to step 13:
660 divided by 81 is 8 with a remainder of 12.
The next digit of our result is 8. 
Result so far: 7957.8148148
If we subtract 648 from 660, 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.

Moving on to step 14:
120 divided by 81 is 1 with a remainder of 39.
Use 1 as the next digit of our solution. 
Result so far: 7957.81481481
Subtract 81 from 120 to get 39.
Since there are no more digits in the dividend, we add a zero to the remainder making it 390, and continue the process.

The final result is 7957.81481481 with a remainder of 3.9e-08.