Let's divide 468858 by 21
The aim is to understand the frequency of 21 in 468858.

Advancing to step 1:
If we divide 4 by 21, we get 0 and a remainder of 4.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 4, we end up with 4.
Bring next digit (6) of the dividend behind the 4 and repeat the process: 46 / 21

Moving on to step 2:
When dividing 46 by 21, we get 2 with a remainder of 4.
Record the quotient 2 as the next digit in the result. 
Result so far: 2.0
If we subtract 42 from 46, we get 4.
Bring next digit (8) of the dividend behind the 4 and repeat the process: 48 / 21

Step 3:
21 goes into 48 2 times with a remainder of 6.
The next digit of our result is 2. 
Result so far: 22.0
The remainder is 6 after subtracting 42 from 48.
Grab the next digit (8) from the dividend, add it to 6, then carry on: 68 / 21

Let's proceed to step 4:
If we divide 68 by 21, we get 3 and a remainder of 5.
Use 3 as the next digit of our solution. 
Result so far: 223.0
Subtract 63 from 68 to get 5.
Take the next digit (5) from the dividend and append it to 5, then repeat: 55 / 21

Going ahead to step 5:
21 can be fit into 55 2 times, resulting in a remainder of 13.
Put 2 as the next digit of the answer. 
Result so far: 2232.0
If we subtract 42 from 55, we get 13.
Bring next digit (8) of the dividend behind the 13 and repeat the process: 138 / 21

Moving on to step 6:
21 can be fit into 138 6 times, resulting in a remainder of 12.
Use 6 as the next digit of our solution. 
Result so far: 22326.0
If we subtract 126 from 138, we 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.

On to step 7:
When dividing 120 by 21, we get 5 with a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 22326.5
Subtract 105 from 120 to 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 8:
The number 21 fits into 150 7 times, leaving a remainder of 3.
Use 7 as the next digit of our solution. 
Result so far: 22326.57
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.

Step 9:
30 divided by 21 is 1 with a remainder of 9.
Put 1 as the next digit of the answer. 
Result so far: 22326.571
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.

Moving on to step 10:
21 goes into 90 4 times with a remainder of 6.
Write down 4 as next digit of the result. 
Result so far: 22326.5714
If we take 84 away from 90, we end up 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.

Advancing to step 11:
When dividing 60 by 21, we get 2 with a remainder of 18.
The next digit of our result is 2. 
Result so far: 22326.57142
If we take 42 away from 60, we end up with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Advancing to step 12:
21 goes into 180 8 times with a remainder of 12.
Record the quotient 8 as the next digit in the result. 
Result so far: 22326.571428
Subtracting 168 from 180 leaves us 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 13:
21 goes into 120 5 times with a remainder of 15.
The next digit of our result is 5. 
Result so far: 22326.5714285
The remainder is 15 after subtracting 105 from 120.
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 14:
The number 21 fits into 150 7 times, leaving a remainder of 3.
Use 7 as the next digit of our solution. 
Result so far: 22326.57142857
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.

The final result is 22326.57142857 with a remainder of 3e-09.