We look at the division of 991257 by 86 
The aim is to understand the frequency of 86 in 991257.

On to step 1:
If we divide 9 by 86, we get 0 and a remainder of 9.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 9, we end up with 9.
Grab the next digit (9) from the dividend, add it to 9, then carry on: 99 / 86

Going ahead to step 2:
When dividing 99 by 86, we get 1 with a remainder of 13.
Write down 1 as next digit of the result. 
Result so far: 1.0
The remainder is 13 after subtracting 86 from 99.
Take the next digit (1) from the dividend and append it to 13, then repeat: 131 / 86

Going ahead to step 3:
86 can be fit into 131 1 times, resulting in a remainder of 45.
The next digit of our result is 1. 
Result so far: 11.0
Subtract 86 from 131 to get 45.
Grab the next digit (2) from the dividend, add it to 45, then carry on: 452 / 86

Going ahead to step 4:
86 goes into 452 5 times with a remainder of 22.
Write down 5 as next digit of the result. 
Result so far: 115.0
If we subtract 430 from 452, we get 22.
Append the next digit (5) from the dividend to 22 and continue with: 225 / 86

Going ahead to step 5:
When dividing 225 by 86, we get 2 with a remainder of 53.
The next digit of our result is 2. 
Result so far: 1152.0
If we subtract 172 from 225, we get 53.
Include the next digit (7) from the dividend after 53, then repeat: 537 / 86

Step 6:
When dividing 537 by 86, we get 6 with a remainder of 21.
Put 6 as the next digit of the answer. 
Result so far: 11526.0
Subtract 516 from 537 to get 21.
Since there are no more digits in the dividend, we add a zero to the remainder making it 210, and continue the process.

Let's proceed to step 7:
If we divide 210 by 86, we get 2 and a remainder of 38.
Write down 2 as next digit of the result. 
Result so far: 11526.2
The remainder is 38 after subtracting 172 from 210.
Since there are no more digits in the dividend, we add a zero to the remainder making it 380, and continue the process.

Moving on to step 8:
86 goes into 380 4 times with a remainder of 36.
Record the quotient 4 as the next digit in the result. 
Result so far: 11526.24
The remainder is 36 after subtracting 344 from 380.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

Moving on to step 9:
When dividing 360 by 86, we get 4 with a remainder of 16.
The number 4 becomes the next digit in our result. 
Result so far: 11526.244
The remainder is 16 after subtracting 344 from 360.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

The final result is 11526.244 with a remainder of 0.0016.