61721 divided by 18 
The aim is to understand the frequency of 18 in 61721.

Advancing to step 1:
6 divided by 18 is 0 with a remainder of 6.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Fetch the next digit (1) from the dividend, attach it to 6 and continue: 61 / 18

Moving on to step 2:
The number 18 fits into 61 3 times, leaving a remainder of 7.
Record the quotient 3 as the next digit in the result. 
Result so far: 3.0
If we take 54 away from 61, we end up with 7.
Bring next digit (7) of the dividend behind the 7 and repeat the process: 77 / 18

Moving on to step 3:
The number 18 fits into 77 4 times, leaving a remainder of 5.
The number 4 becomes the next digit in our result. 
Result so far: 34.0
If we subtract 72 from 77, we get 5.
Grab the next digit (2) from the dividend, add it to 5, then carry on: 52 / 18

Advancing to step 4:
52 divided by 18 is 2 with a remainder of 16.
Write down 2 as next digit of the result. 
Result so far: 342.0
Subtract 36 from 52 to get 16.
Fetch the next digit (1) from the dividend, attach it to 16 and continue: 161 / 18

Step 5:
18 can be fit into 161 8 times, resulting in a remainder of 17.
Record the quotient 8 as the next digit in the result. 
Result so far: 3428.0
The remainder is 17 after subtracting 144 from 161.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Going ahead to step 6:
170 divided by 18 is 9 with a remainder of 8.
Record the quotient 9 as the next digit in the result. 
Result so far: 3428.9
The remainder is 8 after subtracting 162 from 170.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Let's proceed to step 7:
18 goes into 80 4 times with a remainder of 8.
The number 4 becomes the next digit in our result. 
Result so far: 3428.94
If we subtract 72 from 80, we 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.

Moving on to step 8:
When dividing 80 by 18, we get 4 with a remainder of 8.
Put 4 as the next digit of the answer. 
Result so far: 3428.944
If we take 72 away from 80, we end up with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

The final result is 3428.944 with a remainder of 0.0008.