12305900 divided by 521 
The aim is to understand the frequency of 521 in 12305900.

Going ahead to step 1:
The number 521 fits into 1 0 times, leaving a remainder of 1.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 1 leaves us with 1.
Fetch the next digit (2) from the dividend, attach it to 1 and continue: 12 / 521

Let's proceed to step 2:
If we divide 12 by 521, we get 0 and a remainder of 12.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 12 to get 12.
Grab the next digit (3) from the dividend, add it to 12, then carry on: 123 / 521

Advancing to step 3:
When dividing 123 by 521, we get 0 with a remainder of 123.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 123 to get 123.
Take the next digit (0) from the dividend and append it to 123, then repeat: 1230 / 521

Going ahead to step 4:
When dividing 1230 by 521, we get 2 with a remainder of 188.
Write down 2 as next digit of the result. 
Result so far: 2.0
Deduct 1042 from 1230 and we're left with 188.
Take the next digit (5) from the dividend and append it to 188, then repeat: 1885 / 521

Moving on to step 5:
521 can be fit into 1885 3 times, resulting in a remainder of 322.
The next digit of our result is 3. 
Result so far: 23.0
Subtracting 1563 from 1885 leaves us with 322.
Append the next digit (9) from the dividend to 322 and continue with: 3229 / 521

Step 6:
3229 divided by 521 is 6 with a remainder of 103.
The number 6 becomes the next digit in our result. 
Result so far: 236.0
Subtract 3126 from 3229 to get 103.
Grab the next digit (0) from the dividend, add it to 103, then carry on: 1030 / 521

Going ahead to step 7:
When dividing 1030 by 521, we get 1 with a remainder of 509.
Put 1 as the next digit of the answer. 
Result so far: 2361.0
If we subtract 521 from 1030, we get 509.
Take the next digit (0) from the dividend and append it to 509, then repeat: 5090 / 521

On to step 8:
5090 divided by 521 is 9 with a remainder of 401.
The number 9 becomes the next digit in our result. 
Result so far: 23619.0
Deduct 4689 from 5090 and we're left with 401.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4010, and continue the process.

Let's proceed to step 9:
When dividing 4010 by 521, we get 7 with a remainder of 363.
The next digit of our result is 7. 
Result so far: 23619.7
Deduct 3647 from 4010 and we're left with 363.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3630, and continue the process.

Advancing to step 10:
521 can be fit into 3630 6 times, resulting in a remainder of 504.
Put 6 as the next digit of the answer. 
Result so far: 23619.76
Subtract 3126 from 3630 to get 504.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5040, and continue the process.

Step 11:
The number 521 fits into 5040 9 times, leaving a remainder of 351.
Use 9 as the next digit of our solution. 
Result so far: 23619.769
Deduct 4689 from 5040 and we're left with 351.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3510, and continue the process.

Going ahead to step 12:
3510 divided by 521 is 6 with a remainder of 384.
Record the quotient 6 as the next digit in the result. 
Result so far: 23619.7696
Deduct 3126 from 3510 and we're left with 384.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3840, and continue the process.

Moving on to step 13:
521 goes into 3840 7 times with a remainder of 193.
The next digit of our result is 7. 
Result so far: 23619.76967
If we subtract 3647 from 3840, we get 193.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1930, and continue the process.

Advancing to step 14:
If we divide 1930 by 521, we get 3 and a remainder of 367.
The next digit of our result is 3. 
Result so far: 23619.769673
Subtract 1563 from 1930 to get 367.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3670, and continue the process.

Going ahead to step 15:
3670 divided by 521 is 7 with a remainder of 23.
The next digit of our result is 7. 
Result so far: 23619.7696737
If we subtract 3647 from 3670, we get 23.
Since there are no more digits in the dividend, we add a zero to the remainder making it 230, and continue the process.

Advancing to step 16:
230 divided by 521 is 0 with a remainder of 230.
Record the quotient 0 as the next digit in the result. 
Result so far: 23619.7696737
Subtracting 0 from 230 leaves us with 230.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2300, and continue the process.

The quotient of the division is 23619.7696737, and the remainder is 2.3e-07.