992391 divided by 21 
The aim is to understand the frequency of 21 in 992391.

Let's proceed to step 1:
21 goes into 9 0 times with a remainder of 9.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 9 to get 9.
Take the next digit (9) from the dividend and append it to 9, then repeat: 99 / 21

Let's proceed to step 2:
If we divide 99 by 21, we get 4 and a remainder of 15.
Record the quotient 4 as the next digit in the result. 
Result so far: 4.0
Deduct 84 from 99 and we're left with 15.
Bring next digit (2) of the dividend behind the 15 and repeat the process: 152 / 21

On to step 3:
When dividing 152 by 21, we get 7 with a remainder of 5.
The next digit of our result is 7. 
Result so far: 47.0
The remainder is 5 after subtracting 147 from 152.
Bring next digit (3) of the dividend behind the 5 and repeat the process: 53 / 21

Let's proceed to step 4:
When dividing 53 by 21, we get 2 with a remainder of 11.
Write down 2 as next digit of the result. 
Result so far: 472.0
Subtracting 42 from 53 leaves us with 11.
Grab the next digit (9) from the dividend, add it to 11, then carry on: 119 / 21

Step 5:
When dividing 119 by 21, we get 5 with a remainder of 14.
Put 5 as the next digit of the answer. 
Result so far: 4725.0
The remainder is 14 after subtracting 105 from 119.
Append the next digit (1) from the dividend to 14 and continue with: 141 / 21

Step 6:
When dividing 141 by 21, we get 6 with a remainder of 15.
Put 6 as the next digit of the answer. 
Result so far: 47256.0
Subtracting 126 from 141 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.

Step 7:
When dividing 150 by 21, we get 7 with a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 47256.7
If we take 147 away from 150, we end up 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.

Let's proceed to step 8:
If we divide 30 by 21, we get 1 and a remainder of 9.
Use 1 as the next digit of our solution. 
Result so far: 47256.71
Subtract 21 from 30 to 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 9:
If we divide 90 by 21, we get 4 and a remainder of 6.
Write down 4 as next digit of the result. 
Result so far: 47256.714
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.

Going ahead to step 10:
60 divided by 21 is 2 with a remainder of 18.
Put 2 as the next digit of the answer. 
Result so far: 47256.7142
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.

Moving on to step 11:
180 divided by 21 is 8 with a remainder of 12.
The number 8 becomes the next digit in our result. 
Result so far: 47256.71428
Subtract 168 from 180 to get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Step 12:
When dividing 120 by 21, we get 5 with a remainder of 15.
The next digit of our result is 5. 
Result so far: 47256.714285
The remainder is 15 after subtracting 105 from 120.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Advancing to step 13:
21 goes into 150 7 times with a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 47256.7142857
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.

Going ahead to step 14:
When dividing 30 by 21, we get 1 with a remainder of 9.
Use 1 as the next digit of our solution. 
Result so far: 47256.71428571
The remainder is 9 after subtracting 21 from 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

The final outcome is 47256.71428571, with a leftover of 9e-09.