We look at the division of 794413 by 21 
The aim is to understand the frequency of 21 in 794413.

On to step 1:
7 divided by 21 is 0 with a remainder of 7.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 7 and we're left with 7.
Bring next digit (9) of the dividend behind the 7 and repeat the process: 79 / 21

Moving on to step 2:
The number 21 fits into 79 3 times, leaving a remainder of 16.
Put 3 as the next digit of the answer. 
Result so far: 3.0
Deduct 63 from 79 and we're left with 16.
Take the next digit (4) from the dividend and append it to 16, then repeat: 164 / 21

Advancing to step 3:
When dividing 164 by 21, we get 7 with a remainder of 17.
Use 7 as the next digit of our solution. 
Result so far: 37.0
If we take 147 away from 164, we end up with 17.
Append the next digit (4) from the dividend to 17 and continue with: 174 / 21

Let's proceed to step 4:
When dividing 174 by 21, we get 8 with a remainder of 6.
Write down 8 as next digit of the result. 
Result so far: 378.0
Deduct 168 from 174 and we're left with 6.
Include the next digit (1) from the dividend after 6, then repeat: 61 / 21

Going ahead to step 5:
61 divided by 21 is 2 with a remainder of 19.
Use 2 as the next digit of our solution. 
Result so far: 3782.0
Subtract 42 from 61 to get 19.
Bring next digit (3) of the dividend behind the 19 and repeat the process: 193 / 21

Going ahead to step 6:
21 goes into 193 9 times with a remainder of 4.
Record the quotient 9 as the next digit in the result. 
Result so far: 37829.0
Subtract 189 from 193 to 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.

Going ahead to step 7:
21 goes into 40 1 times with a remainder of 19.
Record the quotient 1 as the next digit in the result. 
Result so far: 37829.1
Deduct 21 from 40 and we're left 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.

Step 8:
21 goes into 190 9 times with a remainder of 1.
Record the quotient 9 as the next digit in the result. 
Result so far: 37829.19
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.

On to step 9:
21 can be fit into 10 0 times, resulting in a remainder of 10.
Write down 0 as next digit of the result. 
Result so far: 37829.19
If we take 0 away from 10, we end up 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.
Record the quotient 4 as the next digit in the result. 
Result so far: 37829.1904
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 11:
21 can be fit into 160 7 times, resulting in a remainder of 13.
Write down 7 as next digit of the result. 
Result so far: 37829.19047
Subtract 147 from 160 to 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 12:
21 goes into 130 6 times with a remainder of 4.
The next digit of our result is 6. 
Result so far: 37829.190476
The remainder is 4 after subtracting 126 from 130.
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 13:
40 divided by 21 is 1 with a remainder of 19.
Record the quotient 1 as the next digit in the result. 
Result so far: 37829.1904761
Deduct 21 from 40 and we're left 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.

Going ahead to step 14:
When dividing 190 by 21, we get 9 with a remainder of 1.
The next digit of our result is 9. 
Result so far: 37829.19047619
Subtract 189 from 190 to get 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 outcome is 37829.19047619, with a leftover of 1e-09.