We look at the division of 55158899 by 815 
The aim is to understand the frequency of 815 in 55158899.

Step 1:
815 can be fit into 5 0 times, resulting in a remainder of 5.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 5 to get 5.
Include the next digit (5) from the dividend after 5, then repeat: 55 / 815

Going ahead to step 2:
The number 815 fits into 55 0 times, leaving a remainder of 55.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 55 leaves us with 55.
Fetch the next digit (1) from the dividend, attach it to 55 and continue: 551 / 815

Advancing to step 3:
The number 815 fits into 551 0 times, leaving a remainder of 551.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 551 after subtracting 0 from 551.
Include the next digit (5) from the dividend after 551, then repeat: 5515 / 815

Moving on to step 4:
The number 815 fits into 5515 6 times, leaving a remainder of 625.
Use 6 as the next digit of our solution. 
Result so far: 6.0
Subtract 4890 from 5515 to get 625.
Take the next digit (8) from the dividend and append it to 625, then repeat: 6258 / 815

On to step 5:
If we divide 6258 by 815, we get 7 and a remainder of 553.
Record the quotient 7 as the next digit in the result. 
Result so far: 67.0
If we take 5705 away from 6258, we end up with 553.
Take the next digit (8) from the dividend and append it to 553, then repeat: 5538 / 815

Going ahead to step 6:
If we divide 5538 by 815, we get 6 and a remainder of 648.
Write down 6 as next digit of the result. 
Result so far: 676.0
Deduct 4890 from 5538 and we're left with 648.
Append the next digit (9) from the dividend to 648 and continue with: 6489 / 815

Let's proceed to step 7:
The number 815 fits into 6489 7 times, leaving a remainder of 784.
The number 7 becomes the next digit in our result. 
Result so far: 6767.0
Subtracting 5705 from 6489 leaves us with 784.
Take the next digit (9) from the dividend and append it to 784, then repeat: 7849 / 815

Going ahead to step 8:
If we divide 7849 by 815, we get 9 and a remainder of 514.
Record the quotient 9 as the next digit in the result. 
Result so far: 67679.0
Subtract 7335 from 7849 to get 514.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5140, and continue the process.

Moving on to step 9:
If we divide 5140 by 815, we get 6 and a remainder of 250.
Put 6 as the next digit of the answer. 
Result so far: 67679.6
Subtracting 4890 from 5140 leaves us with 250.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2500, and continue the process.

Moving on to step 10:
2500 divided by 815 is 3 with a remainder of 55.
Record the quotient 3 as the next digit in the result. 
Result so far: 67679.63
If we take 2445 away from 2500, we end up with 55.
Since there are no more digits in the dividend, we add a zero to the remainder making it 550, and continue the process.

On to step 11:
550 divided by 815 is 0 with a remainder of 550.
The next digit of our result is 0. 
Result so far: 67679.63
Deduct 0 from 550 and we're left with 550.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5500, and continue the process.

Moving on to step 12:
The number 815 fits into 5500 6 times, leaving a remainder of 610.
Record the quotient 6 as the next digit in the result. 
Result so far: 67679.6306
Deduct 4890 from 5500 and we're left with 610.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6100, and continue the process.

Going ahead to step 13:
815 goes into 6100 7 times with a remainder of 395.
Use 7 as the next digit of our solution. 
Result so far: 67679.63067
If we take 5705 away from 6100, we end up with 395.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3950, and continue the process.

Advancing to step 14:
The number 815 fits into 3950 4 times, leaving a remainder of 690.
Put 4 as the next digit of the answer. 
Result so far: 67679.630674
Deduct 3260 from 3950 and we're left with 690.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6900, and continue the process.

Step 15:
When dividing 6900 by 815, we get 8 with a remainder of 380.
Write down 8 as next digit of the result. 
Result so far: 67679.6306748
If we take 6520 away from 6900, we end up with 380.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3800, and continue the process.

Going ahead to step 16:
815 can be fit into 3800 4 times, resulting in a remainder of 540.
Use 4 as the next digit of our solution. 
Result so far: 67679.63067484
If we subtract 3260 from 3800, we get 540.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5400, and continue the process.

The final outcome is 67679.63067484, with a leftover of 5.4e-07.