81135421 divided by 393 
The aim is to understand the frequency of 393 in 81135421.

Going ahead to step 1:
If we divide 8 by 393, we get 0 and a remainder of 8.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 8 after subtracting 0 from 8.
Include the next digit (1) from the dividend after 8, then repeat: 81 / 393

Let's proceed to step 2:
81 divided by 393 is 0 with a remainder of 81.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 81, we get 81.
Include the next digit (1) from the dividend after 81, then repeat: 811 / 393

Moving on to step 3:
393 can be fit into 811 2 times, resulting in a remainder of 25.
Record the quotient 2 as the next digit in the result. 
Result so far: 2.0
If we take 786 away from 811, we end up with 25.
Append the next digit (3) from the dividend to 25 and continue with: 253 / 393

Step 4:
393 can be fit into 253 0 times, resulting in a remainder of 253.
The number 0 becomes the next digit in our result. 
Result so far: 20.0
Subtracting 0 from 253 leaves us with 253.
Take the next digit (5) from the dividend and append it to 253, then repeat: 2535 / 393

On to step 5:
2535 divided by 393 is 6 with a remainder of 177.
Use 6 as the next digit of our solution. 
Result so far: 206.0
If we take 2358 away from 2535, we end up with 177.
Include the next digit (4) from the dividend after 177, then repeat: 1774 / 393

On to step 6:
If we divide 1774 by 393, we get 4 and a remainder of 202.
The number 4 becomes the next digit in our result. 
Result so far: 2064.0
If we take 1572 away from 1774, we end up with 202.
Grab the next digit (2) from the dividend, add it to 202, then carry on: 2022 / 393

On to step 7:
393 can be fit into 2022 5 times, resulting in a remainder of 57.
Write down 5 as next digit of the result. 
Result so far: 20645.0
If we subtract 1965 from 2022, we get 57.
Grab the next digit (1) from the dividend, add it to 57, then carry on: 571 / 393

Let's proceed to step 8:
When dividing 571 by 393, we get 1 with a remainder of 178.
The next digit of our result is 1. 
Result so far: 206451.0
Subtracting 393 from 571 leaves us with 178.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1780, and continue the process.

Let's proceed to step 9:
When dividing 1780 by 393, we get 4 with a remainder of 208.
Record the quotient 4 as the next digit in the result. 
Result so far: 206451.4
The remainder is 208 after subtracting 1572 from 1780.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2080, and continue the process.

Step 10:
When dividing 2080 by 393, we get 5 with a remainder of 115.
Put 5 as the next digit of the answer. 
Result so far: 206451.45
If we take 1965 away from 2080, we end up with 115.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1150, and continue the process.

Moving on to step 11:
When dividing 1150 by 393, we get 2 with a remainder of 364.
Use 2 as the next digit of our solution. 
Result so far: 206451.452
If we subtract 786 from 1150, we get 364.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3640, and continue the process.

Advancing to step 12:
If we divide 3640 by 393, we get 9 and a remainder of 103.
The number 9 becomes the next digit in our result. 
Result so far: 206451.4529
Subtracting 3537 from 3640 leaves us with 103.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1030, and continue the process.

On to step 13:
393 goes into 1030 2 times with a remainder of 244.
The number 2 becomes the next digit in our result. 
Result so far: 206451.45292
Deduct 786 from 1030 and we're left with 244.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2440, and continue the process.

Going ahead to step 14:
393 can be fit into 2440 6 times, resulting in a remainder of 82.
The number 6 becomes the next digit in our result. 
Result so far: 206451.452926
Subtracting 2358 from 2440 leaves us with 82.
Since there are no more digits in the dividend, we add a zero to the remainder making it 820, and continue the process.

Advancing to step 15:
393 goes into 820 2 times with a remainder of 34.
Write down 2 as next digit of the result. 
Result so far: 206451.4529262
Subtract 786 from 820 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.

Let's proceed to step 16:
When dividing 340 by 393, we get 0 with a remainder of 340.
The next digit of our result is 0. 
Result so far: 206451.4529262
Deduct 0 from 340 and we're left with 340.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3400, and continue the process.

The final outcome is 206451.4529262, with a leftover of 3.4e-07.