We divide 623463 by 21
The aim is to understand the frequency of 21 in 623463.

Advancing to step 1:
21 goes into 6 0 times with a remainder of 6.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 6, we get 6.
Append the next digit (2) from the dividend to 6 and continue with: 62 / 21

On to step 2:
If we divide 62 by 21, we get 2 and a remainder of 20.
The next digit of our result is 2. 
Result so far: 2.0
Deduct 42 from 62 and we're left with 20.
Append the next digit (3) from the dividend to 20 and continue with: 203 / 21

On to step 3:
If we divide 203 by 21, we get 9 and a remainder of 14.
Put 9 as the next digit of the answer. 
Result so far: 29.0
If we subtract 189 from 203, we get 14.
Include the next digit (4) from the dividend after 14, then repeat: 144 / 21

Let's proceed to step 4:
When dividing 144 by 21, we get 6 with a remainder of 18.
Put 6 as the next digit of the answer. 
Result so far: 296.0
Subtracting 126 from 144 leaves us with 18.
Include the next digit (6) from the dividend after 18, then repeat: 186 / 21

Advancing to step 5:
21 goes into 186 8 times with a remainder of 18.
The number 8 becomes the next digit in our result. 
Result so far: 2968.0
The remainder is 18 after subtracting 168 from 186.
Append the next digit (3) from the dividend to 18 and continue with: 183 / 21

Let's proceed to step 6:
21 goes into 183 8 times with a remainder of 15.
The next digit of our result is 8. 
Result so far: 29688.0
Deduct 168 from 183 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.

On to step 7:
If we divide 150 by 21, we get 7 and a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 29688.7
Deduct 147 from 150 and we're left with 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:
21 can be fit into 30 1 times, resulting in a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 29688.71
The remainder is 9 after subtracting 21 from 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

On to step 9:
If we divide 90 by 21, we get 4 and a remainder of 6.
The next digit of our result is 4. 
Result so far: 29688.714
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.

Step 10:
If we divide 60 by 21, we get 2 and a remainder of 18.
The next digit of our result is 2. 
Result so far: 29688.7142
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.

On to step 11:
When dividing 180 by 21, we get 8 with a remainder of 12.
Record the quotient 8 as the next digit in the result. 
Result so far: 29688.71428
Subtract 168 from 180 to get 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:
The number 21 fits into 120 5 times, leaving a remainder of 15.
Write down 5 as next digit of the result. 
Result so far: 29688.714285
If we subtract 105 from 120, 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.

Advancing to step 13:
When dividing 150 by 21, we get 7 with a remainder of 3.
Record the quotient 7 as the next digit in the result. 
Result so far: 29688.7142857
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.

On to step 14:
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: 29688.71428571
Subtracting 21 from 30 leaves us 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.

The final result is 29688.71428571 with a remainder of 9e-09.