Let's divide 999290 by 21
The aim is to understand the frequency of 21 in 999290.

Step 1:
The number 21 fits into 9 0 times, leaving a remainder of 9.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 9, we end up with 9.
Include the next digit (9) from the dividend after 9, then repeat: 99 / 21

On to step 2:
When dividing 99 by 21, we get 4 with a remainder of 15.
Use 4 as the next digit of our solution. 
Result so far: 4.0
Subtract 84 from 99 to get 15.
Grab the next digit (9) from the dividend, add it to 15, then carry on: 159 / 21

Going ahead to step 3:
21 goes into 159 7 times with a remainder of 12.
The next digit of our result is 7. 
Result so far: 47.0
The remainder is 12 after subtracting 147 from 159.
Bring next digit (2) of the dividend behind the 12 and repeat the process: 122 / 21

Step 4:
When dividing 122 by 21, we get 5 with a remainder of 17.
Put 5 as the next digit of the answer. 
Result so far: 475.0
Subtract 105 from 122 to get 17.
Append the next digit (9) from the dividend to 17 and continue with: 179 / 21

Let's proceed to step 5:
When dividing 179 by 21, we get 8 with a remainder of 11.
Record the quotient 8 as the next digit in the result. 
Result so far: 4758.0
Subtracting 168 from 179 leaves us with 11.
Take the next digit (0) from the dividend and append it to 11, then repeat: 110 / 21

Advancing to step 6:
21 can be fit into 110 5 times, resulting in a remainder of 5.
The next digit of our result is 5. 
Result so far: 47585.0
If we take 105 away from 110, we end up with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Going ahead to step 7:
When dividing 50 by 21, we get 2 with a remainder of 8.
Record the quotient 2 as the next digit in the result. 
Result so far: 47585.2
Subtracting 42 from 50 leaves us with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

On to step 8:
The number 21 fits into 80 3 times, leaving a remainder of 17.
Write down 3 as next digit of the result. 
Result so far: 47585.23
Subtracting 63 from 80 leaves us with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Let's proceed to step 9:
170 divided by 21 is 8 with a remainder of 2.
The number 8 becomes the next digit in our result. 
Result so far: 47585.238
If we take 168 away from 170, we end up with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

On to step 10:
21 can be fit into 20 0 times, resulting in a remainder of 20.
The number 0 becomes the next digit in our result. 
Result so far: 47585.238
Subtracting 0 from 20 leaves us with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Let's proceed to step 11:
When dividing 200 by 21, we get 9 with a remainder of 11.
The number 9 becomes the next digit in our result. 
Result so far: 47585.23809
Subtracting 189 from 200 leaves us with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Step 12:
If we divide 110 by 21, we get 5 and a remainder of 5.
Use 5 as the next digit of our solution. 
Result so far: 47585.238095
If we subtract 105 from 110, we get 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Let's proceed to step 13:
The number 21 fits into 50 2 times, leaving a remainder of 8.
The next digit of our result is 2. 
Result so far: 47585.2380952
Deduct 42 from 50 and we're left with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Step 14:
If we divide 80 by 21, we get 3 and a remainder of 17.
The next digit of our result is 3. 
Result so far: 47585.23809523
Subtract 63 from 80 to get 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

In conclusion, the division gives 47585.23809523 with a balance of 1.7e-08.