We look at the division of 919090 by 31 
The aim is to understand the frequency of 31 in 919090.

Let's proceed to step 1:
When dividing 9 by 31, we get 0 with a remainder of 9.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 9 to get 9.
Grab the next digit (1) from the dividend, add it to 9, then carry on: 91 / 31

Advancing to step 2:
The number 31 fits into 91 2 times, leaving a remainder of 29.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
Subtract 62 from 91 to get 29.
Include the next digit (9) from the dividend after 29, then repeat: 299 / 31

Step 3:
299 divided by 31 is 9 with a remainder of 20.
Use 9 as the next digit of our solution. 
Result so far: 29.0
Subtract 279 from 299 to get 20.
Fetch the next digit (0) from the dividend, attach it to 20 and continue: 200 / 31

Advancing to step 4:
31 can be fit into 200 6 times, resulting in a remainder of 14.
Record the quotient 6 as the next digit in the result. 
Result so far: 296.0
Subtracting 186 from 200 leaves us with 14.
Fetch the next digit (9) from the dividend, attach it to 14 and continue: 149 / 31

Advancing to step 5:
The number 31 fits into 149 4 times, leaving a remainder of 25.
The number 4 becomes the next digit in our result. 
Result so far: 2964.0
Subtracting 124 from 149 leaves us with 25.
Take the next digit (0) from the dividend and append it to 25, then repeat: 250 / 31

Let's proceed to step 6:
If we divide 250 by 31, we get 8 and a remainder of 2.
The next digit of our result is 8. 
Result so far: 29648.0
Deduct 248 from 250 and we're left with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Advancing to step 7:
When dividing 20 by 31, we get 0 with a remainder of 20.
The number 0 becomes the next digit in our result. 
Result so far: 29648.0
Subtracting 0 from 20 leaves us with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Step 8:
31 goes into 200 6 times with a remainder of 14.
The next digit of our result is 6. 
Result so far: 29648.06
Subtract 186 from 200 to get 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

Moving on to step 9:
If we divide 140 by 31, we get 4 and a remainder of 16.
The number 4 becomes the next digit in our result. 
Result so far: 29648.064
If we take 124 away from 140, we end up with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Advancing to step 10:
31 can be fit into 160 5 times, resulting in a remainder of 5.
Write down 5 as next digit of the result. 
Result so far: 29648.0645
The remainder is 5 after subtracting 155 from 160.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Going ahead to step 11:
31 can be fit into 50 1 times, resulting in a remainder of 19.
The next digit of our result is 1. 
Result so far: 29648.06451
The remainder is 19 after subtracting 31 from 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Moving on to step 12:
31 goes into 190 6 times with a remainder of 4.
Put 6 as the next digit of the answer. 
Result so far: 29648.064516
If we subtract 186 from 190, we 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.

Moving on to step 13:
31 goes into 40 1 times with a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 29648.0645161
Subtracting 31 from 40 leaves us 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.

Going ahead to step 14:
90 divided by 31 is 2 with a remainder of 28.
The number 2 becomes the next digit in our result. 
Result so far: 29648.06451612
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.

The final outcome is 29648.06451612, with a leftover of 2.8e-08.