799673 ÷ 21 
The aim is to understand the frequency of 21 in 799673.

Moving on to step 1:
If we divide 7 by 21, we get 0 and a remainder of 7.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 7 leaves us with 7.
Append the next digit (9) from the dividend to 7 and continue with: 79 / 21

On to step 2:
When dividing 79 by 21, we get 3 with a remainder of 16.
The next digit of our result is 3. 
Result so far: 3.0
Subtracting 63 from 79 leaves us with 16.
Include the next digit (9) from the dividend after 16, then repeat: 169 / 21

Advancing to step 3:
When dividing 169 by 21, we get 8 with a remainder of 1.
The next digit of our result is 8. 
Result so far: 38.0
Subtracting 168 from 169 leaves us with 1.
Fetch the next digit (6) from the dividend, attach it to 1 and continue: 16 / 21

Moving on to step 4:
16 divided by 21 is 0 with a remainder of 16.
Put 0 as the next digit of the answer. 
Result so far: 380.0
The remainder is 16 after subtracting 0 from 16.
Include the next digit (7) from the dividend after 16, then repeat: 167 / 21

Going ahead to step 5:
If we divide 167 by 21, we get 7 and a remainder of 20.
Put 7 as the next digit of the answer. 
Result so far: 3807.0
If we subtract 147 from 167, we get 20.
Bring next digit (3) of the dividend behind the 20 and repeat the process: 203 / 21

Let's proceed to step 6:
If we divide 203 by 21, we get 9 and a remainder of 14.
The next digit of our result is 9. 
Result so far: 38079.0
The remainder is 14 after subtracting 189 from 203.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

Step 7:
21 goes into 140 6 times with a remainder of 14.
Use 6 as the next digit of our solution. 
Result so far: 38079.6
The remainder is 14 after subtracting 126 from 140.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

On to step 8:
If we divide 140 by 21, we get 6 and a remainder of 14.
Use 6 as the next digit of our solution. 
Result so far: 38079.66
If we take 126 away from 140, we end up with 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

After the division, we end up with 38079.66 and a remainder of 0.014.