415092 divided by 21 
The aim is to understand the frequency of 21 in 415092.

Step 1:
21 goes into 4 0 times with a remainder of 4.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 4 to get 4.
Append the next digit (1) from the dividend to 4 and continue with: 41 / 21

Advancing to step 2:
41 divided by 21 is 1 with a remainder of 20.
Use 1 as the next digit of our solution. 
Result so far: 1.0
If we subtract 21 from 41, we get 20.
Bring next digit (5) of the dividend behind the 20 and repeat the process: 205 / 21

Moving on to step 3:
When dividing 205 by 21, we get 9 with a remainder of 16.
Use 9 as the next digit of our solution. 
Result so far: 19.0
Subtract 189 from 205 to get 16.
Take the next digit (0) from the dividend and append it to 16, then repeat: 160 / 21

Let's proceed to step 4:
When dividing 160 by 21, we get 7 with a remainder of 13.
The next digit of our result is 7. 
Result so far: 197.0
If we subtract 147 from 160, we get 13.
Take the next digit (9) from the dividend and append it to 13, then repeat: 139 / 21

Going ahead to step 5:
21 goes into 139 6 times with a remainder of 13.
Use 6 as the next digit of our solution. 
Result so far: 1976.0
Subtract 126 from 139 to get 13.
Fetch the next digit (2) from the dividend, attach it to 13 and continue: 132 / 21

Going ahead to step 6:
132 divided by 21 is 6 with a remainder of 6.
Put 6 as the next digit of the answer. 
Result so far: 19766.0
Subtract 126 from 132 to 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.

Advancing to step 7:
When dividing 60 by 21, we get 2 with a remainder of 18.
The number 2 becomes the next digit in our result. 
Result so far: 19766.2
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.

Let's proceed to step 8:
21 goes into 180 8 times with a remainder of 12.
Use 8 as the next digit of our solution. 
Result so far: 19766.28
The remainder is 12 after subtracting 168 from 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Moving on to step 9:
The number 21 fits into 120 5 times, leaving a remainder of 15.
Write down 5 as next digit of the result. 
Result so far: 19766.285
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 10:
150 divided by 21 is 7 with a remainder of 3.
Use 7 as the next digit of our solution. 
Result so far: 19766.2857
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 11:
When dividing 30 by 21, we get 1 with a remainder of 9.
Put 1 as the next digit of the answer. 
Result so far: 19766.28571
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.

Step 12:
If we divide 90 by 21, we get 4 and a remainder of 6.
Use 4 as the next digit of our solution. 
Result so far: 19766.285714
Subtract 84 from 90 to 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.

On to step 13:
21 can be fit into 60 2 times, resulting in a remainder of 18.
Record the quotient 2 as the next digit in the result. 
Result so far: 19766.2857142
Deduct 42 from 60 and we're left with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Let's proceed to step 14:
180 divided by 21 is 8 with a remainder of 12.
The number 8 becomes the next digit in our result. 
Result so far: 19766.28571428
If we take 168 away from 180, we end up 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.

Our division results in 19766.28571428 with a remaining 1.2e-08.