We're dividing 15219166 by 866 
The aim is to understand the frequency of 866 in 15219166.

Advancing to step 1:
If we divide 1 by 866, we get 0 and a remainder of 1.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 1, we end up with 1.
Append the next digit (5) from the dividend to 1 and continue with: 15 / 866

Advancing to step 2:
The number 866 fits into 15 0 times, leaving a remainder of 15.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 15, we get 15.
Append the next digit (2) from the dividend to 15 and continue with: 152 / 866

On to step 3:
866 goes into 152 0 times with a remainder of 152.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 152 after subtracting 0 from 152.
Bring next digit (1) of the dividend behind the 152 and repeat the process: 1521 / 866

On to step 4:
When dividing 1521 by 866, we get 1 with a remainder of 655.
Write down 1 as next digit of the result. 
Result so far: 1.0
If we take 866 away from 1521, we end up with 655.
Take the next digit (9) from the dividend and append it to 655, then repeat: 6559 / 866

Going ahead to step 5:
If we divide 6559 by 866, we get 7 and a remainder of 497.
The next digit of our result is 7. 
Result so far: 17.0
Deduct 6062 from 6559 and we're left with 497.
Include the next digit (1) from the dividend after 497, then repeat: 4971 / 866

Step 6:
The number 866 fits into 4971 5 times, leaving a remainder of 641.
Use 5 as the next digit of our solution. 
Result so far: 175.0
If we subtract 4330 from 4971, we get 641.
Grab the next digit (6) from the dividend, add it to 641, then carry on: 6416 / 866

Step 7:
The number 866 fits into 6416 7 times, leaving a remainder of 354.
Record the quotient 7 as the next digit in the result. 
Result so far: 1757.0
Subtract 6062 from 6416 to get 354.
Append the next digit (6) from the dividend to 354 and continue with: 3546 / 866

Moving on to step 8:
866 goes into 3546 4 times with a remainder of 82.
Write down 4 as next digit of the result. 
Result so far: 17574.0
If we subtract 3464 from 3546, we get 82.
Since there are no more digits in the dividend, we add a zero to the remainder making it 820, and continue the process.

On to step 9:
When dividing 820 by 866, we get 0 with a remainder of 820.
Record the quotient 0 as the next digit in the result. 
Result so far: 17574.0
If we take 0 away from 820, we end up with 820.
Since there are no more digits in the dividend, we add a zero to the remainder making it 8200, and continue the process.

Moving on to step 10:
866 can be fit into 8200 9 times, resulting in a remainder of 406.
Put 9 as the next digit of the answer. 
Result so far: 17574.09
Subtract 7794 from 8200 to get 406.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4060, and continue the process.

Going ahead to step 11:
The number 866 fits into 4060 4 times, leaving a remainder of 596.
Write down 4 as next digit of the result. 
Result so far: 17574.094
Subtracting 3464 from 4060 leaves us with 596.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5960, and continue the process.

Moving on to step 12:
866 can be fit into 5960 6 times, resulting in a remainder of 764.
The number 6 becomes the next digit in our result. 
Result so far: 17574.0946
Deduct 5196 from 5960 and we're left with 764.
Since there are no more digits in the dividend, we add a zero to the remainder making it 7640, and continue the process.

Let's proceed to step 13:
866 goes into 7640 8 times with a remainder of 712.
The number 8 becomes the next digit in our result. 
Result so far: 17574.09468
If we subtract 6928 from 7640, we get 712.
Since there are no more digits in the dividend, we add a zero to the remainder making it 7120, and continue the process.

Advancing to step 14:
When dividing 7120 by 866, we get 8 with a remainder of 192.
The number 8 becomes the next digit in our result. 
Result so far: 17574.094688
Subtracting 6928 from 7120 leaves us with 192.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1920, and continue the process.

After the division, we end up with 17574.094688 and a remainder of 1.92e-05.