Let's divide 907791 by 21
The aim is to understand the frequency of 21 in 907791.

Moving on to step 1:
If we divide 9 by 21, we get 0 and a remainder of 9.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 9 leaves us with 9.
Append the next digit (0) from the dividend to 9 and continue with: 90 / 21

On to step 2:
21 goes into 90 4 times with a remainder of 6.
Put 4 as the next digit of the answer. 
Result so far: 4.0
If we subtract 84 from 90, we get 6.
Include the next digit (7) from the dividend after 6, then repeat: 67 / 21

Going ahead to step 3:
67 divided by 21 is 3 with a remainder of 4.
The next digit of our result is 3. 
Result so far: 43.0
The remainder is 4 after subtracting 63 from 67.
Bring next digit (7) of the dividend behind the 4 and repeat the process: 47 / 21

On to step 4:
21 can be fit into 47 2 times, resulting in a remainder of 5.
The number 2 becomes the next digit in our result. 
Result so far: 432.0
If we take 42 away from 47, we end up with 5.
Fetch the next digit (9) from the dividend, attach it to 5 and continue: 59 / 21

Going ahead to step 5:
21 can be fit into 59 2 times, resulting in a remainder of 17.
Put 2 as the next digit of the answer. 
Result so far: 4322.0
If we subtract 42 from 59, we get 17.
Grab the next digit (1) from the dividend, add it to 17, then carry on: 171 / 21

Let's proceed to step 6:
If we divide 171 by 21, we get 8 and a remainder of 3.
Put 8 as the next digit of the answer. 
Result so far: 43228.0
Deduct 168 from 171 and we're left 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.

Step 7:
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: 43228.1
If we subtract 21 from 30, we 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.

Step 8:
21 goes into 90 4 times with a remainder of 6.
Write down 4 as next digit of the result. 
Result so far: 43228.14
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.

Step 9:
60 divided by 21 is 2 with a remainder of 18.
The next digit of our result is 2. 
Result so far: 43228.142
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 goes into 180 8 times with a remainder of 12.
Put 8 as the next digit of the answer. 
Result so far: 43228.1428
If we subtract 168 from 180, we 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.

Advancing to step 11:
21 goes into 120 5 times with a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 43228.14285
Deduct 105 from 120 and we're left 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:
When dividing 150 by 21, we get 7 with a remainder of 3.
The next digit of our result is 7. 
Result so far: 43228.142857
The remainder is 3 after subtracting 147 from 150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Advancing to step 13:
21 can be fit into 30 1 times, resulting in a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 43228.1428571
Deduct 21 from 30 and we're left with 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 14:
21 goes into 90 4 times with a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 43228.14285714
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.

The quotient of the division is 43228.14285714, and the remainder is 6e-09.