We're dividing 17212001 by 851 
The aim is to understand the frequency of 851 in 17212001.

On to step 1:
If we divide 1 by 851, we get 0 and a remainder of 1.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 1, we end up with 1.
Fetch the next digit (7) from the dividend, attach it to 1 and continue: 17 / 851

Moving on to step 2:
If we divide 17 by 851, we get 0 and a remainder of 17.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 17 after subtracting 0 from 17.
Fetch the next digit (2) from the dividend, attach it to 17 and continue: 172 / 851

Going ahead to step 3:
The number 851 fits into 172 0 times, leaving a remainder of 172.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 172 to get 172.
Append the next digit (1) from the dividend to 172 and continue with: 1721 / 851

Step 4:
851 goes into 1721 2 times with a remainder of 19.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
If we subtract 1702 from 1721, we get 19.
Append the next digit (2) from the dividend to 19 and continue with: 192 / 851

Let's proceed to step 5:
When dividing 192 by 851, we get 0 with a remainder of 192.
Record the quotient 0 as the next digit in the result. 
Result so far: 20.0
Deduct 0 from 192 and we're left with 192.
Grab the next digit (0) from the dividend, add it to 192, then carry on: 1920 / 851

Advancing to step 6:
If we divide 1920 by 851, we get 2 and a remainder of 218.
The number 2 becomes the next digit in our result. 
Result so far: 202.0
Deduct 1702 from 1920 and we're left with 218.
Append the next digit (0) from the dividend to 218 and continue with: 2180 / 851

Advancing to step 7:
851 goes into 2180 2 times with a remainder of 478.
Write down 2 as next digit of the result. 
Result so far: 2022.0
If we subtract 1702 from 2180, we get 478.
Grab the next digit (1) from the dividend, add it to 478, then carry on: 4781 / 851

On to step 8:
851 goes into 4781 5 times with a remainder of 526.
Write down 5 as next digit of the result. 
Result so far: 20225.0
If we subtract 4255 from 4781, we get 526.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5260, and continue the process.

Step 9:
851 goes into 5260 6 times with a remainder of 154.
The next digit of our result is 6. 
Result so far: 20225.6
If we take 5106 away from 5260, we end up with 154.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1540, and continue the process.

Moving on to step 10:
851 can be fit into 1540 1 times, resulting in a remainder of 689.
The next digit of our result is 1. 
Result so far: 20225.61
Subtract 851 from 1540 to get 689.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6890, and continue the process.

Step 11:
If we divide 6890 by 851, we get 8 and a remainder of 82.
Record the quotient 8 as the next digit in the result. 
Result so far: 20225.618
If we subtract 6808 from 6890, we get 82.
Since there are no more digits in the dividend, we add a zero to the remainder making it 820, and continue the process.

On to step 12:
The number 851 fits into 820 0 times, leaving a remainder of 820.
Put 0 as the next digit of the answer. 
Result so far: 20225.618
Subtracting 0 from 820 leaves us with 820.
Since there are no more digits in the dividend, we add a zero to the remainder making it 8200, and continue the process.

Step 13:
When dividing 8200 by 851, we get 9 with a remainder of 541.
The next digit of our result is 9. 
Result so far: 20225.61809
The remainder is 541 after subtracting 7659 from 8200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5410, and continue the process.

Step 14:
If we divide 5410 by 851, we get 6 and a remainder of 304.
Put 6 as the next digit of the answer. 
Result so far: 20225.618096
The remainder is 304 after subtracting 5106 from 5410.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3040, and continue the process.

Moving on to step 15:
When dividing 3040 by 851, we get 3 with a remainder of 487.
Record the quotient 3 as the next digit in the result. 
Result so far: 20225.6180963
Subtracting 2553 from 3040 leaves us with 487.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4870, and continue the process.

Moving on to step 16:
851 goes into 4870 5 times with a remainder of 615.
Use 5 as the next digit of our solution. 
Result so far: 20225.61809635
If we subtract 4255 from 4870, we get 615.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6150, and continue the process.

After the division, we end up with 20225.61809635 and a remainder of 6.15e-07.