86991 ÷ 18 
The aim is to understand the frequency of 18 in 86991.

Step 1:
The number 18 fits into 8 0 times, leaving a remainder of 8.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 8 after subtracting 0 from 8.
Append the next digit (6) from the dividend to 8 and continue with: 86 / 18

On to step 2:
If we divide 86 by 18, we get 4 and a remainder of 14.
Write down 4 as next digit of the result. 
Result so far: 4.0
Subtracting 72 from 86 leaves us with 14.
Bring next digit (9) of the dividend behind the 14 and repeat the process: 149 / 18

Let's proceed to step 3:
The number 18 fits into 149 8 times, leaving a remainder of 5.
Write down 8 as next digit of the result. 
Result so far: 48.0
Deduct 144 from 149 and we're left with 5.
Take the next digit (9) from the dividend and append it to 5, then repeat: 59 / 18

Going ahead to step 4:
When dividing 59 by 18, we get 3 with a remainder of 5.
Use 3 as the next digit of our solution. 
Result so far: 483.0
If we take 54 away from 59, we end up with 5.
Bring next digit (1) of the dividend behind the 5 and repeat the process: 51 / 18

Let's proceed to step 5:
If we divide 51 by 18, we get 2 and a remainder of 15.
Record the quotient 2 as the next digit in the result. 
Result so far: 4832.0
If we take 36 away from 51, we end up with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Going ahead to step 6:
If we divide 150 by 18, we get 8 and a remainder of 6.
The next digit of our result is 8. 
Result so far: 4832.8
If we take 144 away from 150, we end up with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Let's proceed to step 7:
When dividing 60 by 18, we get 3 with a remainder of 6.
The next digit of our result is 3. 
Result so far: 4832.83
Subtracting 54 from 60 leaves us with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Moving on to step 8:
18 can be fit into 60 3 times, resulting in a remainder of 6.
Write down 3 as next digit of the result. 
Result so far: 4832.833
Subtracting 54 from 60 leaves us with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

The quotient of the division is 4832.833, and the remainder is 0.0006.