We're dividing 330500 by 21 
The aim is to understand the frequency of 21 in 330500.

Step 1:
21 goes into 3 0 times with a remainder of 3.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 3 leaves us with 3.
Bring next digit (3) of the dividend behind the 3 and repeat the process: 33 / 21

Advancing to step 2:
The number 21 fits into 33 1 times, leaving a remainder of 12.
Put 1 as the next digit of the answer. 
Result so far: 1.0
Subtract 21 from 33 to get 12.
Include the next digit (0) from the dividend after 12, then repeat: 120 / 21

Let's proceed to step 3:
21 can be fit into 120 5 times, resulting in a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 15.0
If we subtract 105 from 120, we get 15.
Bring next digit (5) of the dividend behind the 15 and repeat the process: 155 / 21

On to step 4:
If we divide 155 by 21, we get 7 and a remainder of 8.
Write down 7 as next digit of the result. 
Result so far: 157.0
Deduct 147 from 155 and we're left with 8.
Append the next digit (0) from the dividend to 8 and continue with: 80 / 21

Let's proceed to step 5:
When dividing 80 by 21, we get 3 with a remainder of 17.
Put 3 as the next digit of the answer. 
Result so far: 1573.0
Deduct 63 from 80 and we're left with 17.
Include the next digit (0) from the dividend after 17, then repeat: 170 / 21

Advancing to step 6:
21 can be fit into 170 8 times, resulting in a remainder of 2.
The number 8 becomes the next digit in our result. 
Result so far: 15738.0
Subtract 168 from 170 to get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Going ahead to step 7:
21 can be fit into 20 0 times, resulting in a remainder of 20.
The next digit of our result is 0. 
Result so far: 15738.0
Deduct 0 from 20 and we're left with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Step 8:
21 goes into 200 9 times with a remainder of 11.
Put 9 as the next digit of the answer. 
Result so far: 15738.09
The remainder is 11 after subtracting 189 from 200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

On to step 9:
The number 21 fits into 110 5 times, leaving a remainder of 5.
The next digit of our result is 5. 
Result so far: 15738.095
Subtracting 105 from 110 leaves us with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Going ahead to step 10:
21 can be fit into 50 2 times, resulting in a remainder of 8.
Record the quotient 2 as the next digit in the result. 
Result so far: 15738.0952
If we subtract 42 from 50, we get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Moving on to step 11:
When dividing 80 by 21, we get 3 with a remainder of 17.
Write down 3 as next digit of the result. 
Result so far: 15738.09523
Deduct 63 from 80 and we're left with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Step 12:
If we divide 170 by 21, we get 8 and a remainder of 2.
Write down 8 as next digit of the result. 
Result so far: 15738.095238
Subtract 168 from 170 to get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Going ahead to step 13:
The number 21 fits into 20 0 times, leaving a remainder of 20.
Write down 0 as next digit of the result. 
Result so far: 15738.095238
Subtracting 0 from 20 leaves us with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Step 14:
21 can be fit into 200 9 times, resulting in a remainder of 11.
Record the quotient 9 as the next digit in the result. 
Result so far: 15738.09523809
Subtracting 189 from 200 leaves us with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

After the division, we end up with 15738.09523809 and a remainder of 1.1e-08.