We look at the division of 812909 by 87 
The aim is to understand the frequency of 87 in 812909.

On to step 1:
When dividing 8 by 87, we get 0 with a remainder of 8.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 8, we end up with 8.
Append the next digit (1) from the dividend to 8 and continue with: 81 / 87

Advancing to step 2:
87 can be fit into 81 0 times, resulting in a remainder of 81.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 81, we end up with 81.
Take the next digit (2) from the dividend and append it to 81, then repeat: 812 / 87

Moving on to step 3:
The number 87 fits into 812 9 times, leaving a remainder of 29.
Put 9 as the next digit of the answer. 
Result so far: 9.0
If we subtract 783 from 812, we get 29.
Fetch the next digit (9) from the dividend, attach it to 29 and continue: 299 / 87

Moving on to step 4:
87 can be fit into 299 3 times, resulting in a remainder of 38.
The number 3 becomes the next digit in our result. 
Result so far: 93.0
Subtract 261 from 299 to get 38.
Take the next digit (0) from the dividend and append it to 38, then repeat: 380 / 87

On to step 5:
If we divide 380 by 87, we get 4 and a remainder of 32.
Record the quotient 4 as the next digit in the result. 
Result so far: 934.0
If we subtract 348 from 380, we get 32.
Include the next digit (9) from the dividend after 32, then repeat: 329 / 87

On to step 6:
87 can be fit into 329 3 times, resulting in a remainder of 68.
The number 3 becomes the next digit in our result. 
Result so far: 9343.0
If we subtract 261 from 329, we get 68.
Since there are no more digits in the dividend, we add a zero to the remainder making it 680, and continue the process.

Advancing to step 7:
87 goes into 680 7 times with a remainder of 71.
Write down 7 as next digit of the result. 
Result so far: 9343.7
The remainder is 71 after subtracting 609 from 680.
Since there are no more digits in the dividend, we add a zero to the remainder making it 710, and continue the process.

Advancing to step 8:
When dividing 710 by 87, we get 8 with a remainder of 14.
The next digit of our result is 8. 
Result so far: 9343.78
If we subtract 696 from 710, we get 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

Advancing to step 9:
The number 87 fits into 140 1 times, leaving a remainder of 53.
Record the quotient 1 as the next digit in the result. 
Result so far: 9343.781
Deduct 87 from 140 and we're left 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.

Let's proceed to step 10:
If we divide 530 by 87, we get 6 and a remainder of 8.
Write down 6 as next digit of the result. 
Result so far: 9343.7816
Subtract 522 from 530 to get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

On to step 11:
When dividing 80 by 87, we get 0 with a remainder of 80.
The next digit of our result is 0. 
Result so far: 9343.7816
Subtracting 0 from 80 leaves us with 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

Moving on to step 12:
The number 87 fits into 800 9 times, leaving a remainder of 17.
Record the quotient 9 as the next digit in the result. 
Result so far: 9343.781609
If we subtract 783 from 800, we get 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

On to step 13:
170 divided by 87 is 1 with a remainder of 83.
The number 1 becomes the next digit in our result. 
Result so far: 9343.7816091
If we subtract 87 from 170, we get 83.
Since there are no more digits in the dividend, we add a zero to the remainder making it 830, and continue the process.

Step 14:
830 divided by 87 is 9 with a remainder of 47.
Record the quotient 9 as the next digit in the result. 
Result so far: 9343.78160919
The remainder is 47 after subtracting 783 from 830.
Since there are no more digits in the dividend, we add a zero to the remainder making it 470, and continue the process.

Our division results in 9343.78160919 with a remaining 4.7e-08.