We're dividing 550993 by 861 
The aim is to understand the frequency of 861 in 550993.

On to step 1:
861 can be fit into 5 0 times, resulting in a remainder of 5.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Include the next digit (5) from the dividend after 5, then repeat: 55 / 861

On to step 2:
When dividing 55 by 861, we get 0 with a remainder of 55.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 55 and we're left with 55.
Bring next digit (0) of the dividend behind the 55 and repeat the process: 550 / 861

Advancing to step 3:
When dividing 550 by 861, we get 0 with a remainder of 550.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 550, we get 550.
Fetch the next digit (9) from the dividend, attach it to 550 and continue: 5509 / 861

Moving on to step 4:
5509 divided by 861 is 6 with a remainder of 343.
Record the quotient 6 as the next digit in the result. 
Result so far: 6.0
The remainder is 343 after subtracting 5166 from 5509.
Append the next digit (9) from the dividend to 343 and continue with: 3439 / 861

Advancing to step 5:
861 can be fit into 3439 3 times, resulting in a remainder of 856.
Use 3 as the next digit of our solution. 
Result so far: 63.0
If we subtract 2583 from 3439, we get 856.
Take the next digit (3) from the dividend and append it to 856, then repeat: 8563 / 861

On to step 6:
8563 divided by 861 is 9 with a remainder of 814.
Put 9 as the next digit of the answer. 
Result so far: 639.0
Subtracting 7749 from 8563 leaves us with 814.
Since there are no more digits in the dividend, we add a zero to the remainder making it 8140, and continue the process.

Step 7:
The number 861 fits into 8140 9 times, leaving a remainder of 391.
Use 9 as the next digit of our solution. 
Result so far: 639.9
The remainder is 391 after subtracting 7749 from 8140.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3910, and continue the process.

Moving on to step 8:
If we divide 3910 by 861, we get 4 and a remainder of 466.
The number 4 becomes the next digit in our result. 
Result so far: 639.94
Deduct 3444 from 3910 and we're left with 466.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4660, and continue the process.

Advancing to step 9:
The number 861 fits into 4660 5 times, leaving a remainder of 355.
Put 5 as the next digit of the answer. 
Result so far: 639.945
Deduct 4305 from 4660 and we're left with 355.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3550, and continue the process.

Let's proceed to step 10:
861 goes into 3550 4 times with a remainder of 106.
Write down 4 as next digit of the result. 
Result so far: 639.9454
Subtract 3444 from 3550 to get 106.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1060, and continue the process.

Moving on to step 11:
861 can be fit into 1060 1 times, resulting in a remainder of 199.
The number 1 becomes the next digit in our result. 
Result so far: 639.94541
If we take 861 away from 1060, we end up with 199.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1990, and continue the process.

On to step 12:
861 goes into 1990 2 times with a remainder of 268.
The number 2 becomes the next digit in our result. 
Result so far: 639.945412
If we take 1722 away from 1990, we end up with 268.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2680, and continue the process.

Going ahead to step 13:
When dividing 2680 by 861, we get 3 with a remainder of 97.
Put 3 as the next digit of the answer. 
Result so far: 639.9454123
Subtracting 2583 from 2680 leaves us with 97.
Since there are no more digits in the dividend, we add a zero to the remainder making it 970, and continue the process.

Going ahead to step 14:
The number 861 fits into 970 1 times, leaving a remainder of 109.
The number 1 becomes the next digit in our result. 
Result so far: 639.94541231
Subtracting 861 from 970 leaves us with 109.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1090, and continue the process.

The final outcome is 639.94541231, with a leftover of 1.09e-07.