218703 ÷ 21 
The aim is to understand the frequency of 21 in 218703.

On to step 1:
If we divide 2 by 21, we get 0 and a remainder of 2.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 2, we get 2.
Append the next digit (1) from the dividend to 2 and continue with: 21 / 21

Going ahead to step 2:
21 divided by 21 is 1 with a remainder of 0.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
The remainder is 0 after subtracting 21 from 21.
Include the next digit (8) from the dividend after 0, then repeat: 8 / 21

Let's proceed to step 3:
21 can be fit into 8 0 times, resulting in a remainder of 8.
The number 0 becomes the next digit in our result. 
Result so far: 10.0
Subtracting 0 from 8 leaves us with 8.
Take the next digit (7) from the dividend and append it to 8, then repeat: 87 / 21

Step 4:
When dividing 87 by 21, we get 4 with a remainder of 3.
Put 4 as the next digit of the answer. 
Result so far: 104.0
Subtracting 84 from 87 leaves us with 3.
Include the next digit (0) from the dividend after 3, then repeat: 30 / 21

Advancing to step 5:
30 divided by 21 is 1 with a remainder of 9.
The number 1 becomes the next digit in our result. 
Result so far: 1041.0
If we take 21 away from 30, we end up with 9.
Bring next digit (3) of the dividend behind the 9 and repeat the process: 93 / 21

Advancing to step 6:
21 can be fit into 93 4 times, resulting in a remainder of 9.
Use 4 as the next digit of our solution. 
Result so far: 10414.0
If we subtract 84 from 93, 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.

On to step 7:
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: 10414.4
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.

Advancing to step 8:
21 can be fit into 60 2 times, resulting in a remainder of 18.
The number 2 becomes the next digit in our result. 
Result so far: 10414.42
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.

Let's proceed to step 9:
The number 21 fits into 180 8 times, leaving a remainder of 12.
Record the quotient 8 as the next digit in the result. 
Result so far: 10414.428
Deduct 168 from 180 and we're left 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.

Let's proceed to step 10:
120 divided by 21 is 5 with a remainder of 15.
The next digit of our result is 5. 
Result so far: 10414.4285
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.

Moving on to step 11:
150 divided by 21 is 7 with a remainder of 3.
Use 7 as the next digit of our solution. 
Result so far: 10414.42857
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.

Moving on to step 12:
The number 21 fits into 30 1 times, leaving a remainder of 9.
Record the quotient 1 as the next digit in the result. 
Result so far: 10414.428571
If we take 21 away from 30, we end up 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.

On to step 13:
21 goes into 90 4 times with a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 10414.4285714
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 14:
21 goes into 60 2 times with a remainder of 18.
Record the quotient 2 as the next digit in the result. 
Result so far: 10414.42857142
The remainder is 18 after subtracting 42 from 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

After the division, we end up with 10414.42857142 and a remainder of 1.8e-08.