We're dividing 912432 by 21 
The aim is to understand the frequency of 21 in 912432.

Moving on to step 1:
If we divide 9 by 21, we get 0 and a remainder of 9.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 9, we end up with 9.
Grab the next digit (1) from the dividend, add it to 9, then carry on: 91 / 21

Let's proceed to step 2:
91 divided by 21 is 4 with a remainder of 7.
Write down 4 as next digit of the result. 
Result so far: 4.0
Subtract 84 from 91 to get 7.
Take the next digit (2) from the dividend and append it to 7, then repeat: 72 / 21

Step 3:
If we divide 72 by 21, we get 3 and a remainder of 9.
Write down 3 as next digit of the result. 
Result so far: 43.0
Deduct 63 from 72 and we're left with 9.
Bring next digit (4) of the dividend behind the 9 and repeat the process: 94 / 21

On to step 4:
When dividing 94 by 21, we get 4 with a remainder of 10.
Put 4 as the next digit of the answer. 
Result so far: 434.0
The remainder is 10 after subtracting 84 from 94.
Include the next digit (3) from the dividend after 10, then repeat: 103 / 21

Step 5:
When dividing 103 by 21, we get 4 with a remainder of 19.
Record the quotient 4 as the next digit in the result. 
Result so far: 4344.0
Subtracting 84 from 103 leaves us with 19.
Append the next digit (2) from the dividend to 19 and continue with: 192 / 21

On to step 6:
The number 21 fits into 192 9 times, leaving a remainder of 3.
The number 9 becomes the next digit in our result. 
Result so far: 43449.0
If we take 189 away from 192, 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.

On to step 7:
21 can be fit into 30 1 times, resulting in a remainder of 9.
The number 1 becomes the next digit in our result. 
Result so far: 43449.1
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.

Let's proceed to step 8:
If we divide 90 by 21, we get 4 and a remainder of 6.
The next digit of our result is 4. 
Result so far: 43449.14
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 9:
21 goes into 60 2 times with a remainder of 18.
The next digit of our result is 2. 
Result so far: 43449.142
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 10:
21 can be fit into 180 8 times, resulting in a remainder of 12.
Use 8 as the next digit of our solution. 
Result so far: 43449.1428
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.

Going ahead to step 11:
When dividing 120 by 21, we get 5 with a remainder of 15.
Use 5 as the next digit of our solution. 
Result so far: 43449.14285
Subtracting 105 from 120 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.

Advancing to step 12:
150 divided by 21 is 7 with a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 43449.142857
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 13:
The number 21 fits into 30 1 times, leaving a remainder of 9.
The next digit of our result is 1. 
Result so far: 43449.1428571
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.

Going ahead to step 14:
When dividing 90 by 21, we get 4 with a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 43449.14285714
If we take 84 away from 90, we end up with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Our division results in 43449.14285714 with a remaining 6e-09.