We look at the division of 511779 by 21 
The aim is to understand the frequency of 21 in 511779.

Moving on to step 1:
If we divide 5 by 21, we get 0 and a remainder of 5.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Bring next digit (1) of the dividend behind the 5 and repeat the process: 51 / 21

Step 2:
21 can be fit into 51 2 times, resulting in a remainder of 9.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
Subtract 42 from 51 to get 9.
Fetch the next digit (1) from the dividend, attach it to 9 and continue: 91 / 21

On to step 3:
When dividing 91 by 21, we get 4 with a remainder of 7.
Write down 4 as next digit of the result. 
Result so far: 24.0
If we take 84 away from 91, we end up with 7.
Append the next digit (7) from the dividend to 7 and continue with: 77 / 21

Moving on to step 4:
The number 21 fits into 77 3 times, leaving a remainder of 14.
Put 3 as the next digit of the answer. 
Result so far: 243.0
If we subtract 63 from 77, we get 14.
Bring next digit (7) of the dividend behind the 14 and repeat the process: 147 / 21

Let's proceed to step 5:
147 divided by 21 is 7 with a remainder of 0.
The next digit of our result is 7. 
Result so far: 2437.0
If we subtract 147 from 147, we get 0.
Take the next digit (9) from the dividend and append it to 0, then repeat: 9 / 21

Step 6:
9 divided by 21 is 0 with a remainder of 9.
The number 0 becomes the next digit in our result. 
Result so far: 24370.0
Deduct 0 from 9 and we're left with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Going ahead to step 7:
If we divide 90 by 21, we get 4 and a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 24370.4
Subtracting 84 from 90 leaves us with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

On to step 8:
21 can be fit into 60 2 times, resulting in a remainder of 18.
The number 2 becomes the next digit in our result. 
Result so far: 24370.42
The remainder is 18 after subtracting 42 from 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Going ahead to step 9:
180 divided by 21 is 8 with a remainder of 12.
Record the quotient 8 as the next digit in the result. 
Result so far: 24370.428
If we take 168 away from 180, we end up with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Step 10:
120 divided by 21 is 5 with a remainder of 15.
Put 5 as the next digit of the answer. 
Result so far: 24370.4285
Deduct 105 from 120 and we're left with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Let's proceed to step 11:
150 divided by 21 is 7 with a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 24370.42857
If we subtract 147 from 150, we get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Moving on to step 12:
30 divided by 21 is 1 with a remainder of 9.
Record the quotient 1 as the next digit in the result. 
Result so far: 24370.428571
Subtract 21 from 30 to get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Advancing to step 13:
90 divided by 21 is 4 with a remainder of 6.
The next digit of our result is 4. 
Result so far: 24370.4285714
If we subtract 84 from 90, we get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Moving on to step 14:
21 goes into 60 2 times with a remainder of 18.
Record the quotient 2 as the next digit in the result. 
Result so far: 24370.42857142
If we subtract 42 from 60, we get 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

In conclusion, the division gives 24370.42857142 with a balance of 1.8e-08.