303269 ÷ 21 
The aim is to understand the frequency of 21 in 303269.

Going ahead to 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
The remainder is 3 after subtracting 0 from 3.
Include the next digit (0) from the dividend after 3, then repeat: 30 / 21

Going ahead to step 2:
If we divide 30 by 21, we get 1 and a remainder of 9.
Put 1 as the next digit of the answer. 
Result so far: 1.0
If we take 21 away from 30, we end up with 9.
Bring next digit (3) of the dividend behind the 9 and repeat the process: 93 / 21

Moving on to step 3:
When dividing 93 by 21, we get 4 with a remainder of 9.
Put 4 as the next digit of the answer. 
Result so far: 14.0
If we take 84 away from 93, we end up with 9.
Bring next digit (2) of the dividend behind the 9 and repeat the process: 92 / 21

Step 4:
21 can be fit into 92 4 times, resulting in a remainder of 8.
The next digit of our result is 4. 
Result so far: 144.0
Deduct 84 from 92 and we're left with 8.
Include the next digit (6) from the dividend after 8, then repeat: 86 / 21

Advancing to step 5:
The number 21 fits into 86 4 times, leaving a remainder of 2.
Record the quotient 4 as the next digit in the result. 
Result so far: 1444.0
If we take 84 away from 86, we end up with 2.
Grab the next digit (9) from the dividend, add it to 2, then carry on: 29 / 21

Moving on to step 6:
When dividing 29 by 21, we get 1 with a remainder of 8.
Write down 1 as next digit of the result. 
Result so far: 14441.0
Deduct 21 from 29 and we're left with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Let's proceed to step 7:
21 goes into 80 3 times with a remainder of 17.
Write down 3 as next digit of the result. 
Result so far: 14441.3
Subtract 63 from 80 to get 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 8:
The number 21 fits into 170 8 times, leaving a remainder of 2.
Use 8 as the next digit of our solution. 
Result so far: 14441.38
If we take 168 away from 170, we end up with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Step 9:
If we divide 20 by 21, we get 0 and a remainder of 20.
Record the quotient 0 as the next digit in the result. 
Result so far: 14441.38
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.

Advancing to step 10:
When dividing 200 by 21, we get 9 with a remainder of 11.
The number 9 becomes the next digit in our result. 
Result so far: 14441.3809
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.

On to step 11:
When dividing 110 by 21, we get 5 with a remainder of 5.
Put 5 as the next digit of the answer. 
Result so far: 14441.38095
If we subtract 105 from 110, we get 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

On to step 12:
When dividing 50 by 21, we get 2 with a remainder of 8.
Write down 2 as next digit of the result. 
Result so far: 14441.380952
If we take 42 away from 50, we end up with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Let's proceed to step 13:
If we divide 80 by 21, we get 3 and a remainder of 17.
Use 3 as the next digit of our solution. 
Result so far: 14441.3809523
Subtract 63 from 80 to get 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Advancing to step 14:
The number 21 fits into 170 8 times, leaving a remainder of 2.
Put 8 as the next digit of the answer. 
Result so far: 14441.38095238
Subtracting 168 from 170 leaves us with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Our division results in 14441.38095238 with a remaining 2e-09.