63849853 ÷ 520 
The aim is to understand the frequency of 520 in 63849853.

Step 1:
When dividing 6 by 520, we get 0 with a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Take the next digit (3) from the dividend and append it to 6, then repeat: 63 / 520

Moving on to step 2:
When dividing 63 by 520, we get 0 with a remainder of 63.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 63, we end up with 63.
Fetch the next digit (8) from the dividend, attach it to 63 and continue: 638 / 520

Let's proceed to step 3:
638 divided by 520 is 1 with a remainder of 118.
Write down 1 as next digit of the result. 
Result so far: 1.0
Subtracting 520 from 638 leaves us with 118.
Include the next digit (4) from the dividend after 118, then repeat: 1184 / 520

Going ahead to step 4:
The number 520 fits into 1184 2 times, leaving a remainder of 144.
The next digit of our result is 2. 
Result so far: 12.0
If we take 1040 away from 1184, we end up with 144.
Fetch the next digit (9) from the dividend, attach it to 144 and continue: 1449 / 520

Advancing to step 5:
520 goes into 1449 2 times with a remainder of 409.
Write down 2 as next digit of the result. 
Result so far: 122.0
The remainder is 409 after subtracting 1040 from 1449.
Append the next digit (8) from the dividend to 409 and continue with: 4098 / 520

Moving on to step 6:
520 can be fit into 4098 7 times, resulting in a remainder of 458.
The number 7 becomes the next digit in our result. 
Result so far: 1227.0
Deduct 3640 from 4098 and we're left with 458.
Bring next digit (5) of the dividend behind the 458 and repeat the process: 4585 / 520

Let's proceed to step 7:
520 can be fit into 4585 8 times, resulting in a remainder of 425.
Put 8 as the next digit of the answer. 
Result so far: 12278.0
If we take 4160 away from 4585, we end up with 425.
Fetch the next digit (3) from the dividend, attach it to 425 and continue: 4253 / 520

On to step 8:
4253 divided by 520 is 8 with a remainder of 93.
Use 8 as the next digit of our solution. 
Result so far: 122788.0
Subtract 4160 from 4253 to get 93.
Since there are no more digits in the dividend, we add a zero to the remainder making it 930, and continue the process.

Let's proceed to step 9:
520 goes into 930 1 times with a remainder of 410.
Write down 1 as next digit of the result. 
Result so far: 122788.1
If we take 520 away from 930, we end up with 410.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4100, and continue the process.

Let's proceed to step 10:
When dividing 4100 by 520, we get 7 with a remainder of 460.
The number 7 becomes the next digit in our result. 
Result so far: 122788.17
The remainder is 460 after subtracting 3640 from 4100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4600, and continue the process.

Step 11:
When dividing 4600 by 520, we get 8 with a remainder of 440.
The number 8 becomes the next digit in our result. 
Result so far: 122788.178
If we subtract 4160 from 4600, we get 440.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4400, and continue the process.

Going ahead to step 12:
The number 520 fits into 4400 8 times, leaving a remainder of 240.
Write down 8 as next digit of the result. 
Result so far: 122788.1788
The remainder is 240 after subtracting 4160 from 4400.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2400, and continue the process.

The final outcome is 122788.1788, with a leftover of 0.0024.