We divide 519809 by 90
The aim is to understand the frequency of 90 in 519809.

Advancing to step 1:
The number 90 fits into 5 0 times, leaving a remainder of 5.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 5 to get 5.
Fetch the next digit (1) from the dividend, attach it to 5 and continue: 51 / 90

Moving on to step 2:
The number 90 fits into 51 0 times, leaving a remainder of 51.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 51 after subtracting 0 from 51.
Append the next digit (9) from the dividend to 51 and continue with: 519 / 90

Step 3:
90 can be fit into 519 5 times, resulting in a remainder of 69.
Record the quotient 5 as the next digit in the result. 
Result so far: 5.0
The remainder is 69 after subtracting 450 from 519.
Append the next digit (8) from the dividend to 69 and continue with: 698 / 90

Let's proceed to step 4:
If we divide 698 by 90, we get 7 and a remainder of 68.
Put 7 as the next digit of the answer. 
Result so far: 57.0
The remainder is 68 after subtracting 630 from 698.
Fetch the next digit (0) from the dividend, attach it to 68 and continue: 680 / 90

On to step 5:
When dividing 680 by 90, we get 7 with a remainder of 50.
Use 7 as the next digit of our solution. 
Result so far: 577.0
If we subtract 630 from 680, we get 50.
Fetch the next digit (9) from the dividend, attach it to 50 and continue: 509 / 90

Let's proceed to step 6:
The number 90 fits into 509 5 times, leaving a remainder of 59.
Use 5 as the next digit of our solution. 
Result so far: 5775.0
Deduct 450 from 509 and we're left with 59.
Since there are no more digits in the dividend, we add a zero to the remainder making it 590, and continue the process.

Step 7:
The number 90 fits into 590 6 times, leaving a remainder of 50.
The number 6 becomes the next digit in our result. 
Result so far: 5775.6
Subtract 540 from 590 to get 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

Going ahead to step 8:
The number 90 fits into 500 5 times, leaving a remainder of 50.
Write down 5 as next digit of the result. 
Result so far: 5775.65
Subtracting 450 from 500 leaves us with 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

Let's proceed to step 9:
When dividing 500 by 90, we get 5 with a remainder of 50.
The number 5 becomes the next digit in our result. 
Result so far: 5775.655
If we subtract 450 from 500, we get 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

After the division, we end up with 5775.655 and a remainder of 0.005.