351216 ÷ 31 
The aim is to understand the frequency of 31 in 351216.

Step 1:
When dividing 3 by 31, we get 0 with a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Deduct 0 from 3 and we're left with 3.
Take the next digit (5) from the dividend and append it to 3, then repeat: 35 / 31

On to step 2:
The number 31 fits into 35 1 times, leaving a remainder of 4.
Put 1 as the next digit of the answer. 
Result so far: 1.0
If we take 31 away from 35, we end up with 4.
Append the next digit (1) from the dividend to 4 and continue with: 41 / 31

Let's proceed to step 3:
31 can be fit into 41 1 times, resulting in a remainder of 10.
Use 1 as the next digit of our solution. 
Result so far: 11.0
Subtract 31 from 41 to get 10.
Append the next digit (2) from the dividend to 10 and continue with: 102 / 31

Advancing to step 4:
102 divided by 31 is 3 with a remainder of 9.
Put 3 as the next digit of the answer. 
Result so far: 113.0
Deduct 93 from 102 and we're left with 9.
Bring next digit (1) of the dividend behind the 9 and repeat the process: 91 / 31

Step 5:
The number 31 fits into 91 2 times, leaving a remainder of 29.
Write down 2 as next digit of the result. 
Result so far: 1132.0
Subtract 62 from 91 to get 29.
Take the next digit (6) from the dividend and append it to 29, then repeat: 296 / 31

Step 6:
296 divided by 31 is 9 with a remainder of 17.
The next digit of our result is 9. 
Result so far: 11329.0
The remainder is 17 after subtracting 279 from 296.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Let's proceed to step 7:
31 goes into 170 5 times with a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 11329.5
If we subtract 155 from 170, we get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Let's proceed to step 8:
31 goes into 150 4 times with a remainder of 26.
Record the quotient 4 as the next digit in the result. 
Result so far: 11329.54
Subtracting 124 from 150 leaves us with 26.
Since there are no more digits in the dividend, we add a zero to the remainder making it 260, and continue the process.

On to step 9:
When dividing 260 by 31, we get 8 with a remainder of 12.
Put 8 as the next digit of the answer. 
Result so far: 11329.548
Subtract 248 from 260 to get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

On to step 10:
The number 31 fits into 120 3 times, leaving a remainder of 27.
Put 3 as the next digit of the answer. 
Result so far: 11329.5483
If we subtract 93 from 120, we get 27.
Since there are no more digits in the dividend, we add a zero to the remainder making it 270, and continue the process.

On to step 11:
31 goes into 270 8 times with a remainder of 22.
The next digit of our result is 8. 
Result so far: 11329.54838
The remainder is 22 after subtracting 248 from 270.
Since there are no more digits in the dividend, we add a zero to the remainder making it 220, and continue the process.

Moving on to step 12:
When dividing 220 by 31, we get 7 with a remainder of 3.
Use 7 as the next digit of our solution. 
Result so far: 11329.548387
If we take 217 away from 220, we end up with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Moving on to step 13:
31 can be fit into 30 0 times, resulting in a remainder of 30.
The number 0 becomes the next digit in our result. 
Result so far: 11329.548387
Subtract 0 from 30 to get 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Let's proceed to step 14:
The number 31 fits into 300 9 times, leaving a remainder of 21.
The next digit of our result is 9. 
Result so far: 11329.54838709
Deduct 279 from 300 and we're left with 21.
Since there are no more digits in the dividend, we add a zero to the remainder making it 210, and continue the process.

After the division, we end up with 11329.54838709 and a remainder of 2.1e-08.