We look at the division of 691649 by 90 
The aim is to understand the frequency of 90 in 691649.

Going ahead to step 1:
90 goes into 6 0 times with a remainder of 6.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 6, we get 6.
Fetch the next digit (9) from the dividend, attach it to 6 and continue: 69 / 90

On to step 2:
If we divide 69 by 90, we get 0 and a remainder of 69.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 69 leaves us with 69.
Grab the next digit (1) from the dividend, add it to 69, then carry on: 691 / 90

Going ahead to step 3:
The number 90 fits into 691 7 times, leaving a remainder of 61.
Use 7 as the next digit of our solution. 
Result so far: 7.0
If we subtract 630 from 691, we get 61.
Include the next digit (6) from the dividend after 61, then repeat: 616 / 90

Let's proceed to step 4:
616 divided by 90 is 6 with a remainder of 76.
Put 6 as the next digit of the answer. 
Result so far: 76.0
Subtracting 540 from 616 leaves us with 76.
Take the next digit (4) from the dividend and append it to 76, then repeat: 764 / 90

On to step 5:
764 divided by 90 is 8 with a remainder of 44.
Put 8 as the next digit of the answer. 
Result so far: 768.0
Deduct 720 from 764 and we're left with 44.
Bring next digit (9) of the dividend behind the 44 and repeat the process: 449 / 90

Going ahead to step 6:
449 divided by 90 is 4 with a remainder of 89.
Put 4 as the next digit of the answer. 
Result so far: 7684.0
The remainder is 89 after subtracting 360 from 449.
Since there are no more digits in the dividend, we add a zero to the remainder making it 890, and continue the process.

Moving on to step 7:
890 divided by 90 is 9 with a remainder of 80.
Write down 9 as next digit of the result. 
Result so far: 7684.9
If we subtract 810 from 890, we get 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

Step 8:
90 can be fit into 800 8 times, resulting in a remainder of 80.
Put 8 as the next digit of the answer. 
Result so far: 7684.98
Deduct 720 from 800 and we're left with 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

Going ahead to step 9:
The number 90 fits into 800 8 times, leaving a remainder of 80.
The next digit of our result is 8. 
Result so far: 7684.988
Subtracting 720 from 800 leaves us with 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

In conclusion, the division gives 7684.988 with a balance of 0.008.