We look at the division of 231377 by 90 
The aim is to understand the frequency of 90 in 231377.

Going ahead to step 1:
90 goes into 2 0 times with a remainder of 2.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 2 and we're left with 2.
Take the next digit (3) from the dividend and append it to 2, then repeat: 23 / 90

Going ahead to step 2:
When dividing 23 by 90, we get 0 with a remainder of 23.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 23 to get 23.
Take the next digit (1) from the dividend and append it to 23, then repeat: 231 / 90

On to step 3:
90 can be fit into 231 2 times, resulting in a remainder of 51.
Write down 2 as next digit of the result. 
Result so far: 2.0
The remainder is 51 after subtracting 180 from 231.
Fetch the next digit (3) from the dividend, attach it to 51 and continue: 513 / 90

Step 4:
The number 90 fits into 513 5 times, leaving a remainder of 63.
Write down 5 as next digit of the result. 
Result so far: 25.0
If we take 450 away from 513, we end up with 63.
Include the next digit (7) from the dividend after 63, then repeat: 637 / 90

Moving on to step 5:
637 divided by 90 is 7 with a remainder of 7.
Write down 7 as next digit of the result. 
Result so far: 257.0
Deduct 630 from 637 and we're left with 7.
Take the next digit (7) from the dividend and append it to 7, then repeat: 77 / 90

Advancing to step 6:
90 goes into 77 0 times with a remainder of 77.
Write down 0 as next digit of the result. 
Result so far: 2570.0
If we subtract 0 from 77, we get 77.
Since there are no more digits in the dividend, we add a zero to the remainder making it 770, and continue the process.

Going ahead to step 7:
The number 90 fits into 770 8 times, leaving a remainder of 50.
Record the quotient 8 as the next digit in the result. 
Result so far: 2570.8
Deduct 720 from 770 and we're left 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.

On to step 8:
The number 90 fits into 500 5 times, leaving a remainder of 50.
Use 5 as the next digit of our solution. 
Result so far: 2570.85
The remainder is 50 after subtracting 450 from 500.
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 9:
90 can be fit into 500 5 times, resulting in a remainder of 50.
Write down 5 as next digit of the result. 
Result so far: 2570.855
Subtract 450 from 500 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.

After the division, we end up with 2570.855 and a remainder of 0.005.