We look at the division of 912172 by 31 
The aim is to understand the frequency of 31 in 912172.

Step 1:
When dividing 9 by 31, we get 0 with 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.
Bring next digit (1) of the dividend behind the 9 and repeat the process: 91 / 31

Let's proceed to step 2:
If we divide 91 by 31, we get 2 and a remainder of 29.
Write down 2 as next digit of the result. 
Result so far: 2.0
If we take 62 away from 91, we end up with 29.
Include the next digit (2) from the dividend after 29, then repeat: 292 / 31

Moving on to step 3:
If we divide 292 by 31, we get 9 and a remainder of 13.
Record the quotient 9 as the next digit in the result. 
Result so far: 29.0
The remainder is 13 after subtracting 279 from 292.
Include the next digit (1) from the dividend after 13, then repeat: 131 / 31

Step 4:
The number 31 fits into 131 4 times, leaving a remainder of 7.
Write down 4 as next digit of the result. 
Result so far: 294.0
The remainder is 7 after subtracting 124 from 131.
Bring next digit (7) of the dividend behind the 7 and repeat the process: 77 / 31

Advancing to step 5:
31 goes into 77 2 times with a remainder of 15.
The next digit of our result is 2. 
Result so far: 2942.0
Deduct 62 from 77 and we're left with 15.
Grab the next digit (2) from the dividend, add it to 15, then carry on: 152 / 31

Going ahead to step 6:
152 divided by 31 is 4 with a remainder of 28.
Use 4 as the next digit of our solution. 
Result so far: 29424.0
If we take 124 away from 152, we end up with 28.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

Step 7:
The number 31 fits into 280 9 times, leaving a remainder of 1.
Put 9 as the next digit of the answer. 
Result so far: 29424.9
The remainder is 1 after subtracting 279 from 280.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Let's proceed to step 8:
31 can be fit into 10 0 times, resulting in a remainder of 10.
The next digit of our result is 0. 
Result so far: 29424.9
The remainder is 10 after subtracting 0 from 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 9:
When dividing 100 by 31, we get 3 with a remainder of 7.
The next digit of our result is 3. 
Result so far: 29424.903
Subtracting 93 from 100 leaves us with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Going ahead to step 10:
70 divided by 31 is 2 with a remainder of 8.
Put 2 as the next digit of the answer. 
Result so far: 29424.9032
If we subtract 62 from 70, 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 11:
If we divide 80 by 31, we get 2 and a remainder of 18.
Use 2 as the next digit of our solution. 
Result so far: 29424.90322
If we take 62 away from 80, we end up with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Our division results in 29424.90322 with a remaining 1.8e-05.