We divide 253817 by 90
The aim is to understand the frequency of 90 in 253817.

Going ahead to step 1:
When dividing 2 by 90, we get 0 with a remainder of 2.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 2, we get 2.
Bring next digit (5) of the dividend behind the 2 and repeat the process: 25 / 90

Moving on to step 2:
The number 90 fits into 25 0 times, leaving a remainder of 25.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Deduct 0 from 25 and we're left with 25.
Take the next digit (3) from the dividend and append it to 25, then repeat: 253 / 90

Moving on to step 3:
253 divided by 90 is 2 with a remainder of 73.
Put 2 as the next digit of the answer. 
Result so far: 2.0
Subtract 180 from 253 to get 73.
Append the next digit (8) from the dividend to 73 and continue with: 738 / 90

Step 4:
90 can be fit into 738 8 times, resulting in a remainder of 18.
Write down 8 as next digit of the result. 
Result so far: 28.0
If we take 720 away from 738, we end up with 18.
Bring next digit (1) of the dividend behind the 18 and repeat the process: 181 / 90

Moving on to step 5:
181 divided by 90 is 2 with a remainder of 1.
Put 2 as the next digit of the answer. 
Result so far: 282.0
If we subtract 180 from 181, we get 1.
Grab the next digit (7) from the dividend, add it to 1, then carry on: 17 / 90

Advancing to step 6:
90 goes into 17 0 times with a remainder of 17.
Put 0 as the next digit of the answer. 
Result so far: 2820.0
The remainder is 17 after subtracting 0 from 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Going ahead to step 7:
When dividing 170 by 90, we get 1 with a remainder of 80.
Write down 1 as next digit of the result. 
Result so far: 2820.1
If we take 90 away from 170, we end up 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.

Step 8:
The number 90 fits into 800 8 times, leaving a remainder of 80.
Put 8 as the next digit of the answer. 
Result so far: 2820.18
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.

Step 9:
When dividing 800 by 90, we get 8 with a remainder of 80.
Use 8 as the next digit of our solution. 
Result so far: 2820.188
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.

After the division, we end up with 2820.188 and a remainder of 0.008.