512041 divided by 21 
The aim is to understand the frequency of 21 in 512041.

Let's proceed to step 1:
21 can be fit into 5 0 times, resulting in a remainder of 5.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 5 leaves us with 5.
Take the next digit (1) from the dividend and append it to 5, then repeat: 51 / 21

Advancing to step 2:
21 can be fit into 51 2 times, resulting in a remainder of 9.
The next digit of our result is 2. 
Result so far: 2.0
The remainder is 9 after subtracting 42 from 51.
Include the next digit (2) from the dividend after 9, then repeat: 92 / 21

Advancing to step 3:
The number 21 fits into 92 4 times, leaving a remainder of 8.
Use 4 as the next digit of our solution. 
Result so far: 24.0
If we subtract 84 from 92, we get 8.
Include the next digit (0) from the dividend after 8, then repeat: 80 / 21

On to step 4:
If we divide 80 by 21, we get 3 and a remainder of 17.
Record the quotient 3 as the next digit in the result. 
Result so far: 243.0
If we take 63 away from 80, we end up with 17.
Append the next digit (4) from the dividend to 17 and continue with: 174 / 21

Step 5:
21 goes into 174 8 times with a remainder of 6.
The number 8 becomes the next digit in our result. 
Result so far: 2438.0
Subtract 168 from 174 to get 6.
Append the next digit (1) from the dividend to 6 and continue with: 61 / 21

Step 6:
The number 21 fits into 61 2 times, leaving a remainder of 19.
Record the quotient 2 as the next digit in the result. 
Result so far: 24382.0
Subtracting 42 from 61 leaves us 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.

Going ahead to step 7:
When dividing 190 by 21, we get 9 with a remainder of 1.
The next digit of our result is 9. 
Result so far: 24382.9
Deduct 189 from 190 and we're left 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.

Advancing to step 8:
21 can be fit into 10 0 times, resulting in a remainder of 10.
The number 0 becomes the next digit in our result. 
Result so far: 24382.9
Deduct 0 from 10 and we're left 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 9:
100 divided by 21 is 4 with a remainder of 16.
The next digit of our result is 4. 
Result so far: 24382.904
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.

Going ahead to step 10:
21 goes into 160 7 times with a remainder of 13.
The next digit of our result is 7. 
Result so far: 24382.9047
If we take 147 away from 160, we end up 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.

Step 11:
21 goes into 130 6 times with a remainder of 4.
Write down 6 as next digit of the result. 
Result so far: 24382.90476
Deduct 126 from 130 and we're left with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Advancing to step 12:
40 divided by 21 is 1 with a remainder of 19.
Use 1 as the next digit of our solution. 
Result so far: 24382.904761
The remainder is 19 after subtracting 21 from 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Moving on to step 13:
21 can be fit into 190 9 times, resulting in a remainder of 1.
The next digit of our result is 9. 
Result so far: 24382.9047619
Subtract 189 from 190 to get 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 14:
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: 24382.9047619
Deduct 0 from 10 and we're left 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.

In conclusion, the division gives 24382.9047619 with a balance of 1e-08.