We divide 661159 by 90
The aim is to understand the frequency of 90 in 661159.

Let's proceed to step 1:
The number 90 fits into 6 0 times, leaving a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 6 to get 6.
Append the next digit (6) from the dividend to 6 and continue with: 66 / 90

Advancing to step 2:
66 divided by 90 is 0 with a remainder of 66.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 66, we get 66.
Take the next digit (1) from the dividend and append it to 66, then repeat: 661 / 90

Moving on to step 3:
90 can be fit into 661 7 times, resulting in a remainder of 31.
The number 7 becomes the next digit in our result. 
Result so far: 7.0
The remainder is 31 after subtracting 630 from 661.
Fetch the next digit (1) from the dividend, attach it to 31 and continue: 311 / 90

Going ahead to step 4:
90 goes into 311 3 times with a remainder of 41.
The number 3 becomes the next digit in our result. 
Result so far: 73.0
Deduct 270 from 311 and we're left with 41.
Include the next digit (5) from the dividend after 41, then repeat: 415 / 90

Let's proceed to step 5:
If we divide 415 by 90, we get 4 and a remainder of 55.
Put 4 as the next digit of the answer. 
Result so far: 734.0
If we take 360 away from 415, we end up with 55.
Bring next digit (9) of the dividend behind the 55 and repeat the process: 559 / 90

On to step 6:
If we divide 559 by 90, we get 6 and a remainder of 19.
Use 6 as the next digit of our solution. 
Result so far: 7346.0
If we take 540 away from 559, we end up with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Let's proceed to step 7:
90 can be fit into 190 2 times, resulting in a remainder of 10.
Record the quotient 2 as the next digit in the result. 
Result so far: 7346.2
Subtract 180 from 190 to get 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 8:
90 can be fit into 100 1 times, resulting in a remainder of 10.
Write down 1 as next digit of the result. 
Result so far: 7346.21
Subtract 90 from 100 to get 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 9:
If we divide 100 by 90, we get 1 and a remainder of 10.
The next digit of our result is 1. 
Result so far: 7346.211
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.

After the division, we end up with 7346.211 and a remainder of 0.001.