We divide 215380 by 90
The aim is to understand the frequency of 90 in 215380.

Advancing to step 1:
If we divide 2 by 90, we get 0 and a remainder of 2.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 2, we end up with 2.
Include the next digit (1) from the dividend after 2, then repeat: 21 / 90

Let's proceed to step 2:
If we divide 21 by 90, we get 0 and a remainder of 21.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 21 after subtracting 0 from 21.
Bring next digit (5) of the dividend behind the 21 and repeat the process: 215 / 90

Advancing to step 3:
The number 90 fits into 215 2 times, leaving a remainder of 35.
The next digit of our result is 2. 
Result so far: 2.0
Deduct 180 from 215 and we're left with 35.
Append the next digit (3) from the dividend to 35 and continue with: 353 / 90

Going ahead to step 4:
90 can be fit into 353 3 times, resulting in a remainder of 83.
Write down 3 as next digit of the result. 
Result so far: 23.0
Deduct 270 from 353 and we're left with 83.
Grab the next digit (8) from the dividend, add it to 83, then carry on: 838 / 90

Step 5:
When dividing 838 by 90, we get 9 with a remainder of 28.
The number 9 becomes the next digit in our result. 
Result so far: 239.0
Subtracting 810 from 838 leaves us with 28.
Take the next digit (0) from the dividend and append it to 28, then repeat: 280 / 90

Step 6:
When dividing 280 by 90, we get 3 with a remainder of 10.
The number 3 becomes the next digit in our result. 
Result so far: 2393.0
If we take 270 away from 280, we end up 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.

On to step 7:
90 goes into 100 1 times with a remainder of 10.
Put 1 as the next digit of the answer. 
Result so far: 2393.1
If we take 90 away from 100, we end up 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.

Moving on to step 8:
100 divided by 90 is 1 with a remainder of 10.
The number 1 becomes the next digit in our result. 
Result so far: 2393.11
If we subtract 90 from 100, we 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.

The final outcome is 2393.11, with a leftover of 0.01.