51607513 divided by 521 
The aim is to understand the frequency of 521 in 51607513.

Moving on to step 1:
521 goes into 5 0 times with a remainder of 5.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 5 and we're left with 5.
Fetch the next digit (1) from the dividend, attach it to 5 and continue: 51 / 521

On to step 2:
When dividing 51 by 521, we get 0 with a remainder of 51.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 51 leaves us with 51.
Include the next digit (6) from the dividend after 51, then repeat: 516 / 521

Moving on to step 3:
If we divide 516 by 521, we get 0 and a remainder of 516.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 516, we get 516.
Include the next digit (0) from the dividend after 516, then repeat: 5160 / 521

Going ahead to step 4:
If we divide 5160 by 521, we get 9 and a remainder of 471.
Use 9 as the next digit of our solution. 
Result so far: 9.0
If we subtract 4689 from 5160, we get 471.
Take the next digit (7) from the dividend and append it to 471, then repeat: 4717 / 521

Going ahead to step 5:
521 goes into 4717 9 times with a remainder of 28.
Use 9 as the next digit of our solution. 
Result so far: 99.0
If we take 4689 away from 4717, we end up with 28.
Bring next digit (5) of the dividend behind the 28 and repeat the process: 285 / 521

Moving on to step 6:
When dividing 285 by 521, we get 0 with a remainder of 285.
Write down 0 as next digit of the result. 
Result so far: 990.0
If we take 0 away from 285, we end up with 285.
Bring next digit (1) of the dividend behind the 285 and repeat the process: 2851 / 521

Let's proceed to step 7:
If we divide 2851 by 521, we get 5 and a remainder of 246.
Record the quotient 5 as the next digit in the result. 
Result so far: 9905.0
Subtract 2605 from 2851 to get 246.
Bring next digit (3) of the dividend behind the 246 and repeat the process: 2463 / 521

Advancing to step 8:
2463 divided by 521 is 4 with a remainder of 379.
The next digit of our result is 4. 
Result so far: 99054.0
The remainder is 379 after subtracting 2084 from 2463.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3790, and continue the process.

On to step 9:
If we divide 3790 by 521, we get 7 and a remainder of 143.
The next digit of our result is 7. 
Result so far: 99054.7
Subtracting 3647 from 3790 leaves us with 143.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1430, and continue the process.

Step 10:
When dividing 1430 by 521, we get 2 with a remainder of 388.
Put 2 as the next digit of the answer. 
Result so far: 99054.72
If we take 1042 away from 1430, we end up with 388.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3880, and continue the process.

Going ahead to step 11:
If we divide 3880 by 521, we get 7 and a remainder of 233.
Write down 7 as next digit of the result. 
Result so far: 99054.727
Subtract 3647 from 3880 to get 233.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2330, and continue the process.

Going ahead to step 12:
2330 divided by 521 is 4 with a remainder of 246.
Use 4 as the next digit of our solution. 
Result so far: 99054.7274
Subtracting 2084 from 2330 leaves us with 246.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2460, and continue the process.

On to step 13:
If we divide 2460 by 521, we get 4 and a remainder of 376.
The next digit of our result is 4. 
Result so far: 99054.72744
Deduct 2084 from 2460 and we're left with 376.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3760, and continue the process.

The final result is 99054.72744 with a remainder of 0.000376.