717427 ÷ 21 
The aim is to understand the frequency of 21 in 717427.

Moving on to step 1:
If we divide 7 by 21, we get 0 and a remainder of 7.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 7, we end up with 7.
Append the next digit (1) from the dividend to 7 and continue with: 71 / 21

Moving on to step 2:
If we divide 71 by 21, we get 3 and a remainder of 8.
The next digit of our result is 3. 
Result so far: 3.0
Subtract 63 from 71 to get 8.
Fetch the next digit (7) from the dividend, attach it to 8 and continue: 87 / 21

Step 3:
87 divided by 21 is 4 with a remainder of 3.
Use 4 as the next digit of our solution. 
Result so far: 34.0
Subtracting 84 from 87 leaves us with 3.
Grab the next digit (4) from the dividend, add it to 3, then carry on: 34 / 21

Moving on to step 4:
34 divided by 21 is 1 with a remainder of 13.
The number 1 becomes the next digit in our result. 
Result so far: 341.0
The remainder is 13 after subtracting 21 from 34.
Bring next digit (2) of the dividend behind the 13 and repeat the process: 132 / 21

Step 5:
21 can be fit into 132 6 times, resulting in a remainder of 6.
The next digit of our result is 6. 
Result so far: 3416.0
If we subtract 126 from 132, we get 6.
Include the next digit (7) from the dividend after 6, then repeat: 67 / 21

Step 6:
If we divide 67 by 21, we get 3 and a remainder of 4.
The number 3 becomes the next digit in our result. 
Result so far: 34163.0
The remainder is 4 after subtracting 63 from 67.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Going ahead to step 7:
When dividing 40 by 21, we get 1 with a remainder of 19.
Record the quotient 1 as the next digit in the result. 
Result so far: 34163.1
Subtract 21 from 40 to 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 8:
190 divided by 21 is 9 with a remainder of 1.
Record the quotient 9 as the next digit in the result. 
Result so far: 34163.19
If we take 189 away from 190, we end up 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.

On to step 9:
The number 21 fits into 10 0 times, leaving a remainder of 10.
Write down 0 as next digit of the result. 
Result so far: 34163.19
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 10:
If we divide 100 by 21, we get 4 and a remainder of 16.
The next digit of our result is 4. 
Result so far: 34163.1904
The remainder is 16 after subtracting 84 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Going ahead to step 11:
160 divided by 21 is 7 with a remainder of 13.
Use 7 as the next digit of our solution. 
Result so far: 34163.19047
Subtracting 147 from 160 leaves us with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Step 12:
If we divide 130 by 21, we get 6 and a remainder of 4.
Use 6 as the next digit of our solution. 
Result so far: 34163.190476
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.

Step 13:
21 can be fit into 40 1 times, resulting in a remainder of 19.
Put 1 as the next digit of the answer. 
Result so far: 34163.1904761
Subtracting 21 from 40 leaves us with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

On to step 14:
When dividing 190 by 21, we get 9 with a remainder of 1.
Record the quotient 9 as the next digit in the result. 
Result so far: 34163.19047619
Subtracting 189 from 190 leaves us 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.

The final result is 34163.19047619 with a remainder of 1e-09.