We're dividing 15485561 by 861 
The aim is to understand the frequency of 861 in 15485561.

Moving on to step 1:
If we divide 1 by 861, we get 0 and a remainder of 1.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 1, we get 1.
Bring next digit (5) of the dividend behind the 1 and repeat the process: 15 / 861

Step 2:
The number 861 fits into 15 0 times, leaving a remainder of 15.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 15, we end up with 15.
Fetch the next digit (4) from the dividend, attach it to 15 and continue: 154 / 861

Advancing to step 3:
If we divide 154 by 861, we get 0 and a remainder of 154.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 154, we get 154.
Fetch the next digit (8) from the dividend, attach it to 154 and continue: 1548 / 861

Step 4:
When dividing 1548 by 861, we get 1 with a remainder of 687.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Deduct 861 from 1548 and we're left with 687.
Grab the next digit (5) from the dividend, add it to 687, then carry on: 6875 / 861

On to step 5:
If we divide 6875 by 861, we get 7 and a remainder of 848.
The next digit of our result is 7. 
Result so far: 17.0
Subtract 6027 from 6875 to get 848.
Bring next digit (5) of the dividend behind the 848 and repeat the process: 8485 / 861

Advancing to step 6:
When dividing 8485 by 861, we get 9 with a remainder of 736.
Put 9 as the next digit of the answer. 
Result so far: 179.0
Subtract 7749 from 8485 to get 736.
Fetch the next digit (6) from the dividend, attach it to 736 and continue: 7366 / 861

Step 7:
861 can be fit into 7366 8 times, resulting in a remainder of 478.
The number 8 becomes the next digit in our result. 
Result so far: 1798.0
If we take 6888 away from 7366, we end up with 478.
Take the next digit (1) from the dividend and append it to 478, then repeat: 4781 / 861

Let's proceed to step 8:
When dividing 4781 by 861, we get 5 with a remainder of 476.
The next digit of our result is 5. 
Result so far: 17985.0
Subtracting 4305 from 4781 leaves us with 476.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4760, and continue the process.

Step 9:
861 goes into 4760 5 times with a remainder of 455.
Use 5 as the next digit of our solution. 
Result so far: 17985.5
Subtract 4305 from 4760 to get 455.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4550, and continue the process.

Step 10:
When dividing 4550 by 861, we get 5 with a remainder of 245.
The next digit of our result is 5. 
Result so far: 17985.55
Subtracting 4305 from 4550 leaves us with 245.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2450, and continue the process.

Our division results in 17985.55 with a remaining 0.245.