We're dividing 18561251 by 221 
The aim is to understand the frequency of 221 in 18561251.

Step 1:
If we divide 1 by 221, we get 0 and a remainder of 1.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 1 after subtracting 0 from 1.
Append the next digit (8) from the dividend to 1 and continue with: 18 / 221

Let's proceed to step 2:
18 divided by 221 is 0 with a remainder of 18.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 18, we end up with 18.
Include the next digit (5) from the dividend after 18, then repeat: 185 / 221

Let's proceed to step 3:
221 goes into 185 0 times with a remainder of 185.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 185 after subtracting 0 from 185.
Append the next digit (6) from the dividend to 185 and continue with: 1856 / 221

Advancing to step 4:
221 goes into 1856 8 times with a remainder of 88.
Write down 8 as next digit of the result. 
Result so far: 8.0
Subtracting 1768 from 1856 leaves us with 88.
Take the next digit (1) from the dividend and append it to 88, then repeat: 881 / 221

Step 5:
If we divide 881 by 221, we get 3 and a remainder of 218.
Write down 3 as next digit of the result. 
Result so far: 83.0
If we take 663 away from 881, we end up with 218.
Include the next digit (2) from the dividend after 218, then repeat: 2182 / 221

Step 6:
221 goes into 2182 9 times with a remainder of 193.
The next digit of our result is 9. 
Result so far: 839.0
Deduct 1989 from 2182 and we're left with 193.
Include the next digit (5) from the dividend after 193, then repeat: 1935 / 221

Going ahead to step 7:
221 can be fit into 1935 8 times, resulting in a remainder of 167.
Put 8 as the next digit of the answer. 
Result so far: 8398.0
Subtract 1768 from 1935 to get 167.
Fetch the next digit (1) from the dividend, attach it to 167 and continue: 1671 / 221

Going ahead to step 8:
When dividing 1671 by 221, we get 7 with a remainder of 124.
The next digit of our result is 7. 
Result so far: 83987.0
Subtract 1547 from 1671 to get 124.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1240, and continue the process.

Step 9:
The number 221 fits into 1240 5 times, leaving a remainder of 135.
Put 5 as the next digit of the answer. 
Result so far: 83987.5
If we take 1105 away from 1240, we end up with 135.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1350, and continue the process.

On to step 10:
When dividing 1350 by 221, we get 6 with a remainder of 24.
Record the quotient 6 as the next digit in the result. 
Result so far: 83987.56
Subtract 1326 from 1350 to get 24.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

On to step 11:
221 can be fit into 240 1 times, resulting in a remainder of 19.
The number 1 becomes the next digit in our result. 
Result so far: 83987.561
If we subtract 221 from 240, we get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Let's proceed to step 12:
When dividing 190 by 221, we get 0 with a remainder of 190.
Use 0 as the next digit of our solution. 
Result so far: 83987.561
If we take 0 away from 190, we end up with 190.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1900, and continue the process.

Moving on to step 13:
1900 divided by 221 is 8 with a remainder of 132.
The next digit of our result is 8. 
Result so far: 83987.56108
If we take 1768 away from 1900, we end up with 132.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1320, and continue the process.

Let's proceed to step 14:
221 can be fit into 1320 5 times, resulting in a remainder of 215.
The next digit of our result is 5. 
Result so far: 83987.561085
If we subtract 1105 from 1320, we get 215.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2150, and continue the process.

Going ahead to step 15:
The number 221 fits into 2150 9 times, leaving a remainder of 161.
Write down 9 as next digit of the result. 
Result so far: 83987.5610859
If we subtract 1989 from 2150, we get 161.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1610, and continue the process.

Step 16:
If we divide 1610 by 221, we get 7 and a remainder of 63.
The number 7 becomes the next digit in our result. 
Result so far: 83987.56108597
Deduct 1547 from 1610 and we're left with 63.
Since there are no more digits in the dividend, we add a zero to the remainder making it 630, and continue the process.

The final result is 83987.56108597 with a remainder of 6.3e-08.