21085990 divided by 813 
The aim is to understand the frequency of 813 in 21085990.

Advancing to step 1:
2 divided by 813 is 0 with a remainder of 2.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 2 to get 2.
Fetch the next digit (1) from the dividend, attach it to 2 and continue: 21 / 813

Let's proceed to step 2:
813 can be fit into 21 0 times, resulting in a remainder of 21.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 21 after subtracting 0 from 21.
Include the next digit (0) from the dividend after 21, then repeat: 210 / 813

On to step 3:
210 divided by 813 is 0 with a remainder of 210.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 210 and we're left with 210.
Include the next digit (8) from the dividend after 210, then repeat: 2108 / 813

Going ahead to step 4:
The number 813 fits into 2108 2 times, leaving a remainder of 482.
Use 2 as the next digit of our solution. 
Result so far: 2.0
Deduct 1626 from 2108 and we're left with 482.
Append the next digit (5) from the dividend to 482 and continue with: 4825 / 813

Let's proceed to step 5:
813 can be fit into 4825 5 times, resulting in a remainder of 760.
The next digit of our result is 5. 
Result so far: 25.0
The remainder is 760 after subtracting 4065 from 4825.
Include the next digit (9) from the dividend after 760, then repeat: 7609 / 813

Step 6:
The number 813 fits into 7609 9 times, leaving a remainder of 292.
Write down 9 as next digit of the result. 
Result so far: 259.0
If we take 7317 away from 7609, we end up with 292.
Bring next digit (9) of the dividend behind the 292 and repeat the process: 2929 / 813

Advancing to step 7:
If we divide 2929 by 813, we get 3 and a remainder of 490.
Put 3 as the next digit of the answer. 
Result so far: 2593.0
Subtracting 2439 from 2929 leaves us with 490.
Append the next digit (0) from the dividend to 490 and continue with: 4900 / 813

Advancing to step 8:
813 goes into 4900 6 times with a remainder of 22.
Use 6 as the next digit of our solution. 
Result so far: 25936.0
Subtract 4878 from 4900 to get 22.
Since there are no more digits in the dividend, we add a zero to the remainder making it 220, and continue the process.

Going ahead to step 9:
If we divide 220 by 813, we get 0 and a remainder of 220.
Put 0 as the next digit of the answer. 
Result so far: 25936.0
If we take 0 away from 220, we end up with 220.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2200, and continue the process.

Advancing to step 10:
813 can be fit into 2200 2 times, resulting in a remainder of 574.
The next digit of our result is 2. 
Result so far: 25936.02
Subtract 1626 from 2200 to get 574.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5740, and continue the process.

Going ahead to step 11:
The number 813 fits into 5740 7 times, leaving a remainder of 49.
Use 7 as the next digit of our solution. 
Result so far: 25936.027
Subtract 5691 from 5740 to get 49.
Since there are no more digits in the dividend, we add a zero to the remainder making it 490, and continue the process.

Step 12:
813 goes into 490 0 times with a remainder of 490.
Write down 0 as next digit of the result. 
Result so far: 25936.027
The remainder is 490 after subtracting 0 from 490.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4900, and continue the process.

Moving on to step 13:
The number 813 fits into 4900 6 times, leaving a remainder of 22.
Use 6 as the next digit of our solution. 
Result so far: 25936.02706
If we subtract 4878 from 4900, we get 22.
Since there are no more digits in the dividend, we add a zero to the remainder making it 220, and continue the process.

Let's proceed to step 14:
813 goes into 220 0 times with a remainder of 220.
The next digit of our result is 0. 
Result so far: 25936.02706
The remainder is 220 after subtracting 0 from 220.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2200, and continue the process.

Step 15:
2200 divided by 813 is 2 with a remainder of 574.
The next digit of our result is 2. 
Result so far: 25936.0270602
Deduct 1626 from 2200 and we're left with 574.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5740, and continue the process.

Moving on to step 16:
The number 813 fits into 5740 7 times, leaving a remainder of 49.
The next digit of our result is 7. 
Result so far: 25936.02706027
Subtracting 5691 from 5740 leaves us with 49.
Since there are no more digits in the dividend, we add a zero to the remainder making it 490, and continue the process.

The final outcome is 25936.02706027, with a leftover of 4.9e-08.