Let's divide 85205121 by 215
The aim is to understand the frequency of 215 in 85205121.

Let's proceed to step 1:
When dividing 8 by 215, we get 0 with a remainder of 8.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 8 to get 8.
Append the next digit (5) from the dividend to 8 and continue with: 85 / 215

Let's proceed to step 2:
If we divide 85 by 215, we get 0 and a remainder of 85.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 85 and we're left with 85.
Take the next digit (2) from the dividend and append it to 85, then repeat: 852 / 215

Moving on to step 3:
215 can be fit into 852 3 times, resulting in a remainder of 207.
The next digit of our result is 3. 
Result so far: 3.0
Subtract 645 from 852 to get 207.
Take the next digit (0) from the dividend and append it to 207, then repeat: 2070 / 215

Moving on to step 4:
215 can be fit into 2070 9 times, resulting in a remainder of 135.
Use 9 as the next digit of our solution. 
Result so far: 39.0
If we subtract 1935 from 2070, we get 135.
Append the next digit (5) from the dividend to 135 and continue with: 1355 / 215

On to step 5:
If we divide 1355 by 215, we get 6 and a remainder of 65.
The next digit of our result is 6. 
Result so far: 396.0
Subtract 1290 from 1355 to get 65.
Bring next digit (1) of the dividend behind the 65 and repeat the process: 651 / 215

Going ahead to step 6:
651 divided by 215 is 3 with a remainder of 6.
Use 3 as the next digit of our solution. 
Result so far: 3963.0
Subtracting 645 from 651 leaves us with 6.
Bring next digit (2) of the dividend behind the 6 and repeat the process: 62 / 215

Going ahead to step 7:
The number 215 fits into 62 0 times, leaving a remainder of 62.
The number 0 becomes the next digit in our result. 
Result so far: 39630.0
The remainder is 62 after subtracting 0 from 62.
Take the next digit (1) from the dividend and append it to 62, then repeat: 621 / 215

Advancing to step 8:
215 goes into 621 2 times with a remainder of 191.
Record the quotient 2 as the next digit in the result. 
Result so far: 396302.0
Subtract 430 from 621 to get 191.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1910, and continue the process.

On to step 9:
215 can be fit into 1910 8 times, resulting in a remainder of 190.
The next digit of our result is 8. 
Result so far: 396302.8
If we subtract 1720 from 1910, we get 190.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1900, and continue the process.

Moving on to step 10:
The number 215 fits into 1900 8 times, leaving a remainder of 180.
Put 8 as the next digit of the answer. 
Result so far: 396302.88
Deduct 1720 from 1900 and we're left with 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1800, and continue the process.

The final result is 396302.88 with a remainder of 0.18.