We're dividing 721987 by 81 
The aim is to understand the frequency of 81 in 721987.

Step 1:
If we divide 7 by 81, we get 0 and a remainder of 7.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 7 after subtracting 0 from 7.
Grab the next digit (2) from the dividend, add it to 7, then carry on: 72 / 81

Advancing to step 2:
The number 81 fits into 72 0 times, leaving a remainder of 72.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 72, we end up with 72.
Include the next digit (1) from the dividend after 72, then repeat: 721 / 81

Advancing to step 3:
721 divided by 81 is 8 with a remainder of 73.
Record the quotient 8 as the next digit in the result. 
Result so far: 8.0
Subtract 648 from 721 to get 73.
Fetch the next digit (9) from the dividend, attach it to 73 and continue: 739 / 81

Advancing to step 4:
The number 81 fits into 739 9 times, leaving a remainder of 10.
The number 9 becomes the next digit in our result. 
Result so far: 89.0
Deduct 729 from 739 and we're left with 10.
Bring next digit (8) of the dividend behind the 10 and repeat the process: 108 / 81

Moving on to step 5:
If we divide 108 by 81, we get 1 and a remainder of 27.
Use 1 as the next digit of our solution. 
Result so far: 891.0
If we take 81 away from 108, we end up with 27.
Bring next digit (7) of the dividend behind the 27 and repeat the process: 277 / 81

Step 6:
81 goes into 277 3 times with a remainder of 34.
Record the quotient 3 as the next digit in the result. 
Result so far: 8913.0
Subtract 243 from 277 to 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.

On to step 7:
The number 81 fits into 340 4 times, leaving a remainder of 16.
Record the quotient 4 as the next digit in the result. 
Result so far: 8913.4
Subtract 324 from 340 to get 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Step 8:
81 goes into 160 1 times with a remainder of 79.
The next digit of our result is 1. 
Result so far: 8913.41
If we take 81 away from 160, we end up 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.

Advancing to step 9:
If we divide 790 by 81, we get 9 and a remainder of 61.
Write down 9 as next digit of the result. 
Result so far: 8913.419
Subtract 729 from 790 to get 61.
Since there are no more digits in the dividend, we add a zero to the remainder making it 610, and continue the process.

Advancing to step 10:
81 goes into 610 7 times with a remainder of 43.
Use 7 as the next digit of our solution. 
Result so far: 8913.4197
Subtracting 567 from 610 leaves us with 43.
Since there are no more digits in the dividend, we add a zero to the remainder making it 430, and continue the process.

Moving on to step 11:
81 goes into 430 5 times with a remainder of 25.
Write down 5 as next digit of the result. 
Result so far: 8913.41975
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.

Moving on to step 12:
The number 81 fits into 250 3 times, leaving a remainder of 7.
Use 3 as the next digit of our solution. 
Result so far: 8913.419753
The remainder is 7 after subtracting 243 from 250.
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:
81 goes into 70 0 times with a remainder of 70.
Write down 0 as next digit of the result. 
Result so far: 8913.419753
Subtracting 0 from 70 leaves us with 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

Advancing to step 14:
81 goes into 700 8 times with a remainder of 52.
The number 8 becomes the next digit in our result. 
Result so far: 8913.41975308
If we subtract 648 from 700, we get 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 quotient of the division is 8913.41975308, and the remainder is 5.2e-08.