We look at the division of 21375 by 31 
The aim is to understand the frequency of 31 in 21375.

Moving on to step 1:
31 goes into 2 0 times with a remainder of 2.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 2 leaves us with 2.
Include the next digit (1) from the dividend after 2, then repeat: 21 / 31

Step 2:
If we divide 21 by 31, we get 0 and a remainder of 21.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 21, we end up with 21.
Grab the next digit (3) from the dividend, add it to 21, then carry on: 213 / 31

Step 3:
213 divided by 31 is 6 with a remainder of 27.
Use 6 as the next digit of our solution. 
Result so far: 6.0
Subtracting 186 from 213 leaves us with 27.
Append the next digit (7) from the dividend to 27 and continue with: 277 / 31

Let's proceed to step 4:
31 goes into 277 8 times with a remainder of 29.
The next digit of our result is 8. 
Result so far: 68.0
Deduct 248 from 277 and we're left with 29.
Take the next digit (5) from the dividend and append it to 29, then repeat: 295 / 31

Going ahead to step 5:
295 divided by 31 is 9 with a remainder of 16.
Record the quotient 9 as the next digit in the result. 
Result so far: 689.0
The remainder is 16 after subtracting 279 from 295.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Moving on to step 6:
When dividing 160 by 31, we get 5 with a remainder of 5.
The next digit of our result is 5. 
Result so far: 689.5
Subtracting 155 from 160 leaves us with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Advancing to step 7:
If we divide 50 by 31, we get 1 and a remainder of 19.
Put 1 as the next digit of the answer. 
Result so far: 689.51
If we take 31 away from 50, we end up with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Advancing to step 8:
The number 31 fits into 190 6 times, leaving a remainder of 4.
Use 6 as the next digit of our solution. 
Result so far: 689.516
Subtract 186 from 190 to get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Going ahead to step 9:
31 can be fit into 40 1 times, resulting in a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 689.5161
Deduct 31 from 40 and we're left with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

On to step 10:
31 can be fit into 90 2 times, resulting in a remainder of 28.
The number 2 becomes the next digit in our result. 
Result so far: 689.51612
Subtracting 62 from 90 leaves us 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 11:
31 goes into 280 9 times with a remainder of 1.
The number 9 becomes the next digit in our result. 
Result so far: 689.516129
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 12:
31 goes into 10 0 times with a remainder of 10.
The number 0 becomes the next digit in our result. 
Result so far: 689.516129
Subtract 0 from 10 to get 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 13:
When dividing 100 by 31, we get 3 with a remainder of 7.
Put 3 as the next digit of the answer. 
Result so far: 689.51612903
If we subtract 93 from 100, we get 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

The final result is 689.51612903 with a remainder of 7e-09.