63711963 ÷ 81 
The aim is to understand the frequency of 81 in 63711963.

Let's proceed to step 1:
When dividing 6 by 81, we get 0 with a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 6 to get 6.
Fetch the next digit (3) from the dividend, attach it to 6 and continue: 63 / 81

Step 2:
The number 81 fits into 63 0 times, leaving a remainder of 63.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 63 after subtracting 0 from 63.
Take the next digit (7) from the dividend and append it to 63, then repeat: 637 / 81

Going ahead to step 3:
The number 81 fits into 637 7 times, leaving a remainder of 70.
Write down 7 as next digit of the result. 
Result so far: 7.0
The remainder is 70 after subtracting 567 from 637.
Append the next digit (1) from the dividend to 70 and continue with: 701 / 81

On to step 4:
701 divided by 81 is 8 with a remainder of 53.
Use 8 as the next digit of our solution. 
Result so far: 78.0
If we take 648 away from 701, we end up with 53.
Include the next digit (1) from the dividend after 53, then repeat: 531 / 81

Going ahead to step 5:
531 divided by 81 is 6 with a remainder of 45.
Record the quotient 6 as the next digit in the result. 
Result so far: 786.0
Subtract 486 from 531 to get 45.
Take the next digit (9) from the dividend and append it to 45, then repeat: 459 / 81

Step 6:
The number 81 fits into 459 5 times, leaving a remainder of 54.
The number 5 becomes the next digit in our result. 
Result so far: 7865.0
Deduct 405 from 459 and we're left with 54.
Take the next digit (6) from the dividend and append it to 54, then repeat: 546 / 81

Advancing to step 7:
If we divide 546 by 81, we get 6 and a remainder of 60.
Write down 6 as next digit of the result. 
Result so far: 78656.0
If we subtract 486 from 546, we get 60.
Include the next digit (3) from the dividend after 60, then repeat: 603 / 81

Advancing to step 8:
If we divide 603 by 81, we get 7 and a remainder of 36.
The next digit of our result is 7. 
Result so far: 786567.0
Subtract 567 from 603 to get 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

Let's proceed to step 9:
When dividing 360 by 81, we get 4 with a remainder of 36.
Use 4 as the next digit of our solution. 
Result so far: 786567.4
Subtract 324 from 360 to get 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

On to step 10:
81 goes into 360 4 times with a remainder of 36.
Record the quotient 4 as the next digit in the result. 
Result so far: 786567.44
Subtract 324 from 360 to get 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

The final outcome is 786567.44, with a leftover of 0.036.