We divide 573203 by 21
The aim is to understand the frequency of 21 in 573203.

Advancing to step 1:
When dividing 5 by 21, we get 0 with a remainder of 5.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 5, we end up with 5.
Take the next digit (7) from the dividend and append it to 5, then repeat: 57 / 21

Advancing to step 2:
The number 21 fits into 57 2 times, leaving a remainder of 15.
Use 2 as the next digit of our solution. 
Result so far: 2.0
Subtracting 42 from 57 leaves us with 15.
Grab the next digit (3) from the dividend, add it to 15, then carry on: 153 / 21

Going ahead to step 3:
21 can be fit into 153 7 times, resulting in a remainder of 6.
The next digit of our result is 7. 
Result so far: 27.0
If we subtract 147 from 153, we get 6.
Append the next digit (2) from the dividend to 6 and continue with: 62 / 21

Going ahead to step 4:
When dividing 62 by 21, we get 2 with a remainder of 20.
Use 2 as the next digit of our solution. 
Result so far: 272.0
Subtracting 42 from 62 leaves us with 20.
Take the next digit (0) from the dividend and append it to 20, then repeat: 200 / 21

Going ahead to step 5:
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: 2729.0
Subtract 189 from 200 to get 11.
Take the next digit (3) from the dividend and append it to 11, then repeat: 113 / 21

On to step 6:
21 can be fit into 113 5 times, resulting in a remainder of 8.
Write down 5 as next digit of the result. 
Result so far: 27295.0
Subtracting 105 from 113 leaves us 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:
80 divided by 21 is 3 with a remainder of 17.
Use 3 as the next digit of our solution. 
Result so far: 27295.3
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.

Advancing to 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: 27295.38
Deduct 168 from 170 and we're left 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.

Going ahead to step 9:
21 goes into 20 0 times with a remainder of 20.
Write down 0 as next digit of the result. 
Result so far: 27295.38
The remainder is 20 after subtracting 0 from 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

On to step 10:
The number 21 fits into 200 9 times, leaving a remainder of 11.
The next digit of our result is 9. 
Result so far: 27295.3809
If we take 189 away from 200, we end up 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.

Advancing to step 11:
21 can be fit into 110 5 times, resulting in a remainder of 5.
The next digit of our result is 5. 
Result so far: 27295.38095
If we take 105 away from 110, we end up with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Let's proceed 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: 27295.380952
If we subtract 42 from 50, we get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Step 13:
The number 21 fits into 80 3 times, leaving a remainder of 17.
Put 3 as the next digit of the answer. 
Result so far: 27295.3809523
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:
When dividing 170 by 21, we get 8 with a remainder of 2.
The number 8 becomes the next digit in our result. 
Result so far: 27295.38095238
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 27295.38095238 with a remaining 2e-09.