686799 divided by 81 
The aim is to understand the frequency of 81 in 686799.

Moving on to step 1:
If we divide 6 by 81, we get 0 and a remainder of 6.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Bring next digit (8) of the dividend behind the 6 and repeat the process: 68 / 81

Moving on to step 2:
81 can be fit into 68 0 times, resulting in a remainder of 68.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 68 to get 68.
Include the next digit (6) from the dividend after 68, then repeat: 686 / 81

Step 3:
If we divide 686 by 81, we get 8 and a remainder of 38.
Record the quotient 8 as the next digit in the result. 
Result so far: 8.0
Subtracting 648 from 686 leaves us with 38.
Grab the next digit (7) from the dividend, add it to 38, then carry on: 387 / 81

Step 4:
81 goes into 387 4 times with a remainder of 63.
Put 4 as the next digit of the answer. 
Result so far: 84.0
If we subtract 324 from 387, we get 63.
Fetch the next digit (9) from the dividend, attach it to 63 and continue: 639 / 81

On to step 5:
81 can be fit into 639 7 times, resulting in a remainder of 72.
Record the quotient 7 as the next digit in the result. 
Result so far: 847.0
Subtract 567 from 639 to get 72.
Include the next digit (9) from the dividend after 72, then repeat: 729 / 81

Step 6:
The number 81 fits into 729 9 times, leaving a remainder of 0.
The next digit of our result is 9. 
Result so far: 8479.0
Subtracting 729 from 729 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

On to step 7:
81 can be fit into 0 0 times, resulting in a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 8479.0
Deduct 0 from 0 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing to step 8:
81 goes into 0 0 times with a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 8479.0
Deduct 0 from 0 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final outcome is 8479.0, with a leftover of 0.0.