We look at the division of 912139 by 30 
The aim is to understand the frequency of 30 in 912139.

On to step 1:
When dividing 9 by 30, we get 0 with a remainder of 9.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 9, we get 9.
Grab the next digit (1) from the dividend, add it to 9, then carry on: 91 / 30

Advancing to step 2:
If we divide 91 by 30, we get 3 and a remainder of 1.
The number 3 becomes the next digit in our result. 
Result so far: 3.0
If we take 90 away from 91, we end up with 1.
Include the next digit (2) from the dividend after 1, then repeat: 12 / 30

Going ahead to step 3:
30 goes into 12 0 times with a remainder of 12.
Record the quotient 0 as the next digit in the result. 
Result so far: 30.0
Subtracting 0 from 12 leaves us with 12.
Include the next digit (1) from the dividend after 12, then repeat: 121 / 30

Advancing to step 4:
30 goes into 121 4 times with a remainder of 1.
Write down 4 as next digit of the result. 
Result so far: 304.0
Deduct 120 from 121 and we're left with 1.
Take the next digit (3) from the dividend and append it to 1, then repeat: 13 / 30

Let's proceed to step 5:
The number 30 fits into 13 0 times, leaving a remainder of 13.
Write down 0 as next digit of the result. 
Result so far: 3040.0
The remainder is 13 after subtracting 0 from 13.
Append the next digit (9) from the dividend to 13 and continue with: 139 / 30

Going ahead to step 6:
When dividing 139 by 30, we get 4 with a remainder of 19.
Record the quotient 4 as the next digit in the result. 
Result so far: 30404.0
The remainder is 19 after subtracting 120 from 139.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

On to step 7:
When dividing 190 by 30, we get 6 with a remainder of 10.
Put 6 as the next digit of the answer. 
Result so far: 30404.6
Subtracting 180 from 190 leaves us with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Let's proceed to step 8:
If we divide 100 by 30, we get 3 and a remainder of 10.
Record the quotient 3 as the next digit in the result. 
Result so far: 30404.63
Deduct 90 from 100 and we're left with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Advancing to step 9:
When dividing 100 by 30, we get 3 with a remainder of 10.
The number 3 becomes the next digit in our result. 
Result so far: 30404.633
The remainder is 10 after subtracting 90 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

The final result is 30404.633 with a remainder of 0.001.