757998 divided by 21 
The aim is to understand the frequency of 21 in 757998.

Advancing to step 1:
When dividing 7 by 21, we get 0 with a remainder of 7.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 7 leaves us with 7.
Bring next digit (5) of the dividend behind the 7 and repeat the process: 75 / 21

Moving on to step 2:
The number 21 fits into 75 3 times, leaving a remainder of 12.
The number 3 becomes the next digit in our result. 
Result so far: 3.0
If we take 63 away from 75, we end up with 12.
Include the next digit (7) from the dividend after 12, then repeat: 127 / 21

Going ahead to step 3:
When dividing 127 by 21, we get 6 with a remainder of 1.
Put 6 as the next digit of the answer. 
Result so far: 36.0
The remainder is 1 after subtracting 126 from 127.
Fetch the next digit (9) from the dividend, attach it to 1 and continue: 19 / 21

Going ahead to step 4:
19 divided by 21 is 0 with a remainder of 19.
Put 0 as the next digit of the answer. 
Result so far: 360.0
Deduct 0 from 19 and we're left with 19.
Take the next digit (9) from the dividend and append it to 19, then repeat: 199 / 21

Advancing to step 5:
When dividing 199 by 21, we get 9 with a remainder of 10.
Write down 9 as next digit of the result. 
Result so far: 3609.0
Subtract 189 from 199 to get 10.
Bring next digit (8) of the dividend behind the 10 and repeat the process: 108 / 21

Let's proceed to step 6:
The number 21 fits into 108 5 times, leaving a remainder of 3.
Write down 5 as next digit of the result. 
Result so far: 36095.0
Subtracting 105 from 108 leaves us 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.

Step 7:
The number 21 fits into 30 1 times, leaving a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 36095.1
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.

Step 8:
The number 21 fits into 90 4 times, leaving a remainder of 6.
The next digit of our result is 4. 
Result so far: 36095.14
If we subtract 84 from 90, we get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Let's proceed to step 9:
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: 36095.142
Subtract 42 from 60 to 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.

Going ahead to step 10:
21 can be fit into 180 8 times, resulting in a remainder of 12.
Use 8 as the next digit of our solution. 
Result so far: 36095.1428
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.

Let's proceed to step 11:
When dividing 120 by 21, we get 5 with a remainder of 15.
Record the quotient 5 as the next digit in the result. 
Result so far: 36095.14285
If we take 105 away from 120, we end up 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.

Going ahead to step 12:
21 goes into 150 7 times with a remainder of 3.
The next digit of our result is 7. 
Result so far: 36095.142857
The remainder is 3 after subtracting 147 from 150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Advancing to step 13:
When dividing 30 by 21, we get 1 with a remainder of 9.
The next digit of our result is 1. 
Result so far: 36095.1428571
If we subtract 21 from 30, 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.

Moving on to step 14:
21 can be fit into 90 4 times, resulting in a remainder of 6.
The number 4 becomes the next digit in our result. 
Result so far: 36095.14285714
Deduct 84 from 90 and we're left 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.

In conclusion, the division gives 36095.14285714 with a balance of 6e-09.