We look at the division of 18865509 by 391 
The aim is to understand the frequency of 391 in 18865509.

Let's proceed to step 1:
When dividing 1 by 391, we get 0 with a remainder of 1.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 1 after subtracting 0 from 1.
Fetch the next digit (8) from the dividend, attach it to 1 and continue: 18 / 391

Moving on to step 2:
The number 391 fits into 18 0 times, leaving a remainder of 18.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 18, we end up with 18.
Include the next digit (8) from the dividend after 18, then repeat: 188 / 391

Moving on to step 3:
When dividing 188 by 391, we get 0 with a remainder of 188.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 188 leaves us with 188.
Append the next digit (6) from the dividend to 188 and continue with: 1886 / 391

Step 4:
1886 divided by 391 is 4 with a remainder of 322.
Put 4 as the next digit of the answer. 
Result so far: 4.0
Deduct 1564 from 1886 and we're left with 322.
Bring next digit (5) of the dividend behind the 322 and repeat the process: 3225 / 391

Advancing to step 5:
3225 divided by 391 is 8 with a remainder of 97.
The number 8 becomes the next digit in our result. 
Result so far: 48.0
If we take 3128 away from 3225, we end up with 97.
Fetch the next digit (5) from the dividend, attach it to 97 and continue: 975 / 391

Step 6:
When dividing 975 by 391, we get 2 with a remainder of 193.
The number 2 becomes the next digit in our result. 
Result so far: 482.0
Subtracting 782 from 975 leaves us with 193.
Grab the next digit (0) from the dividend, add it to 193, then carry on: 1930 / 391

Advancing to step 7:
391 goes into 1930 4 times with a remainder of 366.
Write down 4 as next digit of the result. 
Result so far: 4824.0
Deduct 1564 from 1930 and we're left with 366.
Take the next digit (9) from the dividend and append it to 366, then repeat: 3669 / 391

Going ahead to step 8:
The number 391 fits into 3669 9 times, leaving a remainder of 150.
Use 9 as the next digit of our solution. 
Result so far: 48249.0
Subtract 3519 from 3669 to get 150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1500, and continue the process.

Going ahead to step 9:
391 goes into 1500 3 times with a remainder of 327.
Write down 3 as next digit of the result. 
Result so far: 48249.3
Subtracting 1173 from 1500 leaves us with 327.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3270, and continue the process.

Moving on to step 10:
3270 divided by 391 is 8 with a remainder of 142.
Use 8 as the next digit of our solution. 
Result so far: 48249.38
Subtracting 3128 from 3270 leaves us with 142.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1420, and continue the process.

Going ahead to step 11:
1420 divided by 391 is 3 with a remainder of 247.
Use 3 as the next digit of our solution. 
Result so far: 48249.383
Subtract 1173 from 1420 to get 247.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2470, and continue the process.

Let's proceed to step 12:
When dividing 2470 by 391, we get 6 with a remainder of 124.
Write down 6 as next digit of the result. 
Result so far: 48249.3836
Subtracting 2346 from 2470 leaves us with 124.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1240, and continue the process.

Let's proceed to step 13:
1240 divided by 391 is 3 with a remainder of 67.
Use 3 as the next digit of our solution. 
Result so far: 48249.38363
Subtracting 1173 from 1240 leaves us with 67.
Since there are no more digits in the dividend, we add a zero to the remainder making it 670, and continue the process.

On to step 14:
When dividing 670 by 391, we get 1 with a remainder of 279.
Use 1 as the next digit of our solution. 
Result so far: 48249.383631
If we subtract 391 from 670, we get 279.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2790, and continue the process.

Advancing to step 15:
If we divide 2790 by 391, we get 7 and a remainder of 53.
Put 7 as the next digit of the answer. 
Result so far: 48249.3836317
If we take 2737 away from 2790, we end up with 53.
Since there are no more digits in the dividend, we add a zero to the remainder making it 530, and continue the process.

Step 16:
When dividing 530 by 391, we get 1 with a remainder of 139.
Write down 1 as next digit of the result. 
Result so far: 48249.38363171
If we take 391 away from 530, we end up with 139.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1390, and continue the process.

Our division results in 48249.38363171 with a remaining 1.39e-07.