We look at the division of 463569 by 21 
The aim is to understand the frequency of 21 in 463569.

On to step 1:
4 divided by 21 is 0 with a remainder of 4.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 4 leaves us with 4.
Include the next digit (6) from the dividend after 4, then repeat: 46 / 21

Step 2:
21 can be fit into 46 2 times, resulting in a remainder of 4.
Use 2 as the next digit of our solution. 
Result so far: 2.0
Subtract 42 from 46 to get 4.
Grab the next digit (3) from the dividend, add it to 4, then carry on: 43 / 21

Going ahead to step 3:
If we divide 43 by 21, we get 2 and a remainder of 1.
Write down 2 as next digit of the result. 
Result so far: 22.0
Subtract 42 from 43 to get 1.
Grab the next digit (5) from the dividend, add it to 1, then carry on: 15 / 21

Let's proceed to step 4:
The number 21 fits into 15 0 times, leaving a remainder of 15.
Put 0 as the next digit of the answer. 
Result so far: 220.0
Subtract 0 from 15 to get 15.
Grab the next digit (6) from the dividend, add it to 15, then carry on: 156 / 21

Let's proceed to step 5:
When dividing 156 by 21, we get 7 with a remainder of 9.
The next digit of our result is 7. 
Result so far: 2207.0
Subtracting 147 from 156 leaves us with 9.
Include the next digit (9) from the dividend after 9, then repeat: 99 / 21

On to step 6:
21 can be fit into 99 4 times, resulting in a remainder of 15.
Record the quotient 4 as the next digit in the result. 
Result so far: 22074.0
If we subtract 84 from 99, we get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Going ahead to step 7:
21 can be fit into 150 7 times, resulting in a remainder of 3.
Put 7 as the next digit of the answer. 
Result so far: 22074.7
Subtract 147 from 150 to 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.

Going ahead to step 8:
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: 22074.71
If we subtract 21 from 30, we 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.

Going ahead to step 9:
When dividing 90 by 21, we get 4 with a remainder of 6.
The number 4 becomes the next digit in our result. 
Result so far: 22074.714
The remainder is 6 after subtracting 84 from 90.
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 10:
When dividing 60 by 21, we get 2 with a remainder of 18.
Record the quotient 2 as the next digit in the result. 
Result so far: 22074.7142
Subtract 42 from 60 to 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.

Going ahead to step 11:
The number 21 fits into 180 8 times, leaving a remainder of 12.
Use 8 as the next digit of our solution. 
Result so far: 22074.71428
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.

Going ahead to step 12:
When dividing 120 by 21, we get 5 with a remainder of 15.
Put 5 as the next digit of the answer. 
Result so far: 22074.714285
Subtracting 105 from 120 leaves us 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.

Going ahead to step 13:
The number 21 fits into 150 7 times, leaving a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 22074.7142857
Subtract 147 from 150 to 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.

Let's proceed to step 14:
30 divided by 21 is 1 with a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 22074.71428571
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.

The final outcome is 22074.71428571, with a leftover of 9e-09.