993634 ÷ 21 
The aim is to understand the frequency of 21 in 993634.

Step 1:
When dividing 9 by 21, we get 0 with a remainder of 9.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 9 leaves us with 9.
Fetch the next digit (9) from the dividend, attach it to 9 and continue: 99 / 21

Moving on to step 2:
When dividing 99 by 21, we get 4 with a remainder of 15.
The number 4 becomes the next digit in our result. 
Result so far: 4.0
Subtract 84 from 99 to get 15.
Grab the next digit (3) from the dividend, add it to 15, then carry on: 153 / 21

Going ahead to step 3:
21 goes into 153 7 times with a remainder of 6.
Put 7 as the next digit of the answer. 
Result so far: 47.0
Deduct 147 from 153 and we're left with 6.
Grab the next digit (6) from the dividend, add it to 6, then carry on: 66 / 21

Step 4:
If we divide 66 by 21, we get 3 and a remainder of 3.
Write down 3 as next digit of the result. 
Result so far: 473.0
Deduct 63 from 66 and we're left with 3.
Include the next digit (3) from the dividend after 3, then repeat: 33 / 21

Step 5:
If we divide 33 by 21, we get 1 and a remainder of 12.
The next digit of our result is 1. 
Result so far: 4731.0
Deduct 21 from 33 and we're left with 12.
Take the next digit (4) from the dividend and append it to 12, then repeat: 124 / 21

Advancing to step 6:
When dividing 124 by 21, we get 5 with a remainder of 19.
Record the quotient 5 as the next digit in the result. 
Result so far: 47315.0
If we subtract 105 from 124, we get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Moving on to step 7:
When dividing 190 by 21, we get 9 with a remainder of 1.
The next digit of our result is 9. 
Result so far: 47315.9
Deduct 189 from 190 and we're left with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Let's proceed to step 8:
If we divide 10 by 21, we get 0 and a remainder of 10.
The next digit of our result is 0. 
Result so far: 47315.9
Subtracting 0 from 10 leaves us with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Let's proceed to step 9:
When dividing 100 by 21, we get 4 with a remainder of 16.
Use 4 as the next digit of our solution. 
Result so far: 47315.904
If we take 84 away from 100, we end up with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Advancing to step 10:
160 divided by 21 is 7 with a remainder of 13.
The number 7 becomes the next digit in our result. 
Result so far: 47315.9047
If we subtract 147 from 160, we get 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Let's proceed to step 11:
21 can be fit into 130 6 times, resulting in a remainder of 4.
Record the quotient 6 as the next digit in the result. 
Result so far: 47315.90476
If we subtract 126 from 130, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Moving on to step 12:
21 can be fit into 40 1 times, resulting in a remainder of 19.
Use 1 as the next digit of our solution. 
Result so far: 47315.904761
The remainder is 19 after subtracting 21 from 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Step 13:
21 can be fit into 190 9 times, resulting in a remainder of 1.
The number 9 becomes the next digit in our result. 
Result so far: 47315.9047619
The remainder is 1 after subtracting 189 from 190.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Let's proceed to step 14:
10 divided by 21 is 0 with a remainder of 10.
The next digit of our result is 0. 
Result so far: 47315.9047619
If we subtract 0 from 10, we get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

The final result is 47315.9047619 with a remainder of 1e-08.