452944 divided by 21 
The aim is to understand the frequency of 21 in 452944.

Let's proceed to step 1:
If we divide 4 by 21, we get 0 and a remainder of 4.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 4 to get 4.
Take the next digit (5) from the dividend and append it to 4, then repeat: 45 / 21

Advancing to step 2:
45 divided by 21 is 2 with a remainder of 3.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
Subtract 42 from 45 to get 3.
Include the next digit (2) from the dividend after 3, then repeat: 32 / 21

Moving on to step 3:
21 goes into 32 1 times with a remainder of 11.
The next digit of our result is 1. 
Result so far: 21.0
Deduct 21 from 32 and we're left with 11.
Include the next digit (9) from the dividend after 11, then repeat: 119 / 21

Step 4:
The number 21 fits into 119 5 times, leaving a remainder of 14.
The number 5 becomes the next digit in our result. 
Result so far: 215.0
Subtract 105 from 119 to get 14.
Take the next digit (4) from the dividend and append it to 14, then repeat: 144 / 21

Going ahead to step 5:
The number 21 fits into 144 6 times, leaving a remainder of 18.
Use 6 as the next digit of our solution. 
Result so far: 2156.0
If we take 126 away from 144, we end up with 18.
Grab the next digit (4) from the dividend, add it to 18, then carry on: 184 / 21

Going ahead to step 6:
If we divide 184 by 21, we get 8 and a remainder of 16.
Record the quotient 8 as the next digit in the result. 
Result so far: 21568.0
If we take 168 away from 184, we end up 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.

Advancing to step 7:
160 divided by 21 is 7 with a remainder of 13.
The number 7 becomes the next digit in our result. 
Result so far: 21568.7
If we subtract 147 from 160, we get 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Advancing to step 8:
The number 21 fits into 130 6 times, leaving a remainder of 4.
Use 6 as the next digit of our solution. 
Result so far: 21568.76
If we take 126 away from 130, we end up 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.

On to step 9:
40 divided by 21 is 1 with a remainder of 19.
The next digit of our result is 1. 
Result so far: 21568.761
If we subtract 21 from 40, we get 19.
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 10:
190 divided by 21 is 9 with a remainder of 1.
Put 9 as the next digit of the answer. 
Result so far: 21568.7619
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.

Let's proceed to step 11:
If we divide 10 by 21, we get 0 and a remainder of 10.
Put 0 as the next digit of the answer. 
Result so far: 21568.7619
If we take 0 away from 10, we end up 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.

Moving on to step 12:
When dividing 100 by 21, we get 4 with a remainder of 16.
The next digit of our result is 4. 
Result so far: 21568.761904
The remainder is 16 after subtracting 84 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Let's proceed to step 13:
160 divided by 21 is 7 with a remainder of 13.
Record the quotient 7 as the next digit in the result. 
Result so far: 21568.7619047
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.

Let's proceed to step 14:
21 can be fit into 130 6 times, resulting in a remainder of 4.
Put 6 as the next digit of the answer. 
Result so far: 21568.76190476
If we subtract 126 from 130, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Our division results in 21568.76190476 with a remaining 4e-09.