Let's divide 17302591 by 21
The aim is to understand the frequency of 21 in 17302591.

On to step 1:
21 can be fit into 1 0 times, resulting in a remainder of 1.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 1 leaves us with 1.
Append the next digit (7) from the dividend to 1 and continue with: 17 / 21

Moving on to step 2:
17 divided by 21 is 0 with a remainder of 17.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 17 to get 17.
Include the next digit (3) from the dividend after 17, then repeat: 173 / 21

On to step 3:
When dividing 173 by 21, we get 8 with a remainder of 5.
The next digit of our result is 8. 
Result so far: 8.0
If we subtract 168 from 173, we get 5.
Fetch the next digit (0) from the dividend, attach it to 5 and continue: 50 / 21

Advancing to step 4:
50 divided by 21 is 2 with a remainder of 8.
The next digit of our result is 2. 
Result so far: 82.0
If we take 42 away from 50, we end up with 8.
Take the next digit (2) from the dividend and append it to 8, then repeat: 82 / 21

Step 5:
The number 21 fits into 82 3 times, leaving a remainder of 19.
Use 3 as the next digit of our solution. 
Result so far: 823.0
If we take 63 away from 82, we end up with 19.
Take the next digit (5) from the dividend and append it to 19, then repeat: 195 / 21

Moving on to step 6:
21 goes into 195 9 times with a remainder of 6.
The next digit of our result is 9. 
Result so far: 8239.0
If we subtract 189 from 195, we get 6.
Grab the next digit (9) from the dividend, add it to 6, then carry on: 69 / 21

Advancing to step 7:
When dividing 69 by 21, we get 3 with a remainder of 6.
The number 3 becomes the next digit in our result. 
Result so far: 82393.0
Subtract 63 from 69 to get 6.
Include the next digit (1) from the dividend after 6, then repeat: 61 / 21

Advancing to step 8:
21 goes into 61 2 times with a remainder of 19.
The next digit of our result is 2. 
Result so far: 823932.0
If we subtract 42 from 61, we get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Step 9:
190 divided by 21 is 9 with a remainder of 1.
Use 9 as the next digit of our solution. 
Result so far: 823932.9
If we take 189 away from 190, we end up with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Let's proceed to step 10:
21 goes into 10 0 times with a remainder of 10.
Record the quotient 0 as the next digit in the result. 
Result so far: 823932.9
Subtracting 0 from 10 leaves us 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.

Let's proceed to step 11:
When dividing 100 by 21, we get 4 with a remainder of 16.
Record the quotient 4 as the next digit in the result. 
Result so far: 823932.904
Subtracting 84 from 100 leaves us with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Let's proceed to step 12:
160 divided by 21 is 7 with a remainder of 13.
The number 7 becomes the next digit in our result. 
Result so far: 823932.9047
Deduct 147 from 160 and we're left with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Advancing to step 13:
The number 21 fits into 130 6 times, leaving a remainder of 4.
Write down 6 as next digit of the result. 
Result so far: 823932.90476
If we subtract 126 from 130, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Going ahead to step 14:
The number 21 fits into 40 1 times, leaving a remainder of 19.
The next digit of our result is 1. 
Result so far: 823932.904761
If we take 21 away from 40, we end up with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Advancing to step 15:
21 goes into 190 9 times with a remainder of 1.
Put 9 as the next digit of the answer. 
Result so far: 823932.9047619
Subtracting 189 from 190 leaves us with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Going ahead to step 16:
If we divide 10 by 21, we get 0 and a remainder of 10.
Put 0 as the next digit of the answer. 
Result so far: 823932.9047619
If we subtract 0 from 10, 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.

Our division results in 823932.9047619 with a remaining 1e-08.