We look at the division of 173220 by 12 
The aim is to understand the frequency of 12 in 173220.

On to step 1:
12 goes into 1 0 times with a remainder of 1.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 1, we get 1.
Include the next digit (7) from the dividend after 1, then repeat: 17 / 12

Step 2:
17 divided by 12 is 1 with a remainder of 5.
Put 1 as the next digit of the answer. 
Result so far: 1.0
Deduct 12 from 17 and we're left with 5.
Append the next digit (3) from the dividend to 5 and continue with: 53 / 12

Step 3:
The number 12 fits into 53 4 times, leaving a remainder of 5.
The number 4 becomes the next digit in our result. 
Result so far: 14.0
The remainder is 5 after subtracting 48 from 53.
Include the next digit (2) from the dividend after 5, then repeat: 52 / 12

Advancing to step 4:
12 goes into 52 4 times with a remainder of 4.
The number 4 becomes the next digit in our result. 
Result so far: 144.0
The remainder is 4 after subtracting 48 from 52.
Grab the next digit (2) from the dividend, add it to 4, then carry on: 42 / 12

Advancing to step 5:
The number 12 fits into 42 3 times, leaving a remainder of 6.
Put 3 as the next digit of the answer. 
Result so far: 1443.0
The remainder is 6 after subtracting 36 from 42.
Fetch the next digit (0) from the dividend, attach it to 6 and continue: 60 / 12

Advancing to step 6:
60 divided by 12 is 5 with a remainder of 0.
Put 5 as the next digit of the answer. 
Result so far: 14435.0
Deduct 60 from 60 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Step 7:
12 goes into 0 0 times with a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 14435.0
The remainder is 0 after subtracting 0 from 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Moving on to step 8:
12 can be fit into 0 0 times, resulting in a remainder of 0.
The next digit of our result is 0. 
Result so far: 14435.0
The remainder is 0 after subtracting 0 from 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The quotient of the division is 14435.0, and the remainder is 0.0.