707924 divided by 21 
The aim is to understand the frequency of 21 in 707924.

Let's proceed to step 1:
7 divided by 21 is 0 with a remainder of 7.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we subtract 0 from 7, we get 7.
Take the next digit (0) from the dividend and append it to 7, then repeat: 70 / 21

Step 2:
21 can be fit into 70 3 times, resulting in a remainder of 7.
Put 3 as the next digit of the answer. 
Result so far: 3.0
The remainder is 7 after subtracting 63 from 70.
Grab the next digit (7) from the dividend, add it to 7, then carry on: 77 / 21

On to step 3:
If we divide 77 by 21, we get 3 and a remainder of 14.
Put 3 as the next digit of the answer. 
Result so far: 33.0
If we take 63 away from 77, we end up with 14.
Append the next digit (9) from the dividend to 14 and continue with: 149 / 21

Going ahead to step 4:
If we divide 149 by 21, we get 7 and a remainder of 2.
The next digit of our result is 7. 
Result so far: 337.0
Subtracting 147 from 149 leaves us with 2.
Fetch the next digit (2) from the dividend, attach it to 2 and continue: 22 / 21

Let's proceed to step 5:
The number 21 fits into 22 1 times, leaving a remainder of 1.
Use 1 as the next digit of our solution. 
Result so far: 3371.0
If we take 21 away from 22, we end up with 1.
Fetch the next digit (4) from the dividend, attach it to 1 and continue: 14 / 21

Advancing to step 6:
The number 21 fits into 14 0 times, leaving a remainder of 14.
Put 0 as the next digit of the answer. 
Result so far: 33710.0
Subtracting 0 from 14 leaves us 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.

Let's proceed to step 7:
140 divided by 21 is 6 with a remainder of 14.
Put 6 as the next digit of the answer. 
Result so far: 33710.6
If we subtract 126 from 140, we get 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

Step 8:
21 can be fit into 140 6 times, resulting in a remainder of 14.
Use 6 as the next digit of our solution. 
Result so far: 33710.66
Deduct 126 from 140 and we're left 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.

The final result is 33710.66 with a remainder of 0.014.