599713 divided by 90 
The aim is to understand the frequency of 90 in 599713.

Going ahead to step 1:
5 divided by 90 is 0 with a remainder of 5.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 5 and we're left with 5.
Include the next digit (9) from the dividend after 5, then repeat: 59 / 90

Moving on to step 2:
The number 90 fits into 59 0 times, leaving a remainder of 59.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 59 and we're left with 59.
Append the next digit (9) from the dividend to 59 and continue with: 599 / 90

Going ahead to step 3:
When dividing 599 by 90, we get 6 with a remainder of 59.
Use 6 as the next digit of our solution. 
Result so far: 6.0
The remainder is 59 after subtracting 540 from 599.
Include the next digit (7) from the dividend after 59, then repeat: 597 / 90

Advancing to step 4:
When dividing 597 by 90, we get 6 with a remainder of 57.
The number 6 becomes the next digit in our result. 
Result so far: 66.0
Subtract 540 from 597 to get 57.
Fetch the next digit (1) from the dividend, attach it to 57 and continue: 571 / 90

Advancing to step 5:
When dividing 571 by 90, we get 6 with a remainder of 31.
Put 6 as the next digit of the answer. 
Result so far: 666.0
Deduct 540 from 571 and we're left with 31.
Fetch the next digit (3) from the dividend, attach it to 31 and continue: 313 / 90

Let's proceed to step 6:
If we divide 313 by 90, we get 3 and a remainder of 43.
The number 3 becomes the next digit in our result. 
Result so far: 6663.0
If we subtract 270 from 313, we get 43.
Since there are no more digits in the dividend, we add a zero to the remainder making it 430, and continue the process.

Moving on to step 7:
When dividing 430 by 90, we get 4 with a remainder of 70.
Put 4 as the next digit of the answer. 
Result so far: 6663.4
If we take 360 away from 430, we end up with 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

On to step 8:
When dividing 700 by 90, we get 7 with a remainder of 70.
Put 7 as the next digit of the answer. 
Result so far: 6663.47
If we subtract 630 from 700, we get 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

On to step 9:
The number 90 fits into 700 7 times, leaving a remainder of 70.
Write down 7 as next digit of the result. 
Result so far: 6663.477
The remainder is 70 after subtracting 630 from 700.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

After the division, we end up with 6663.477 and a remainder of 0.007.