We're dividing 39151598 by 521 
The aim is to understand the frequency of 521 in 39151598.

On to step 1:
When dividing 3 by 521, we get 0 with a remainder of 3.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 3, we get 3.
Grab the next digit (9) from the dividend, add it to 3, then carry on: 39 / 521

Advancing to step 2:
521 goes into 39 0 times with a remainder of 39.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 39 after subtracting 0 from 39.
Include the next digit (1) from the dividend after 39, then repeat: 391 / 521

Advancing to step 3:
The number 521 fits into 391 0 times, leaving a remainder of 391.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 391 to get 391.
Grab the next digit (5) from the dividend, add it to 391, then carry on: 3915 / 521

Going ahead to step 4:
If we divide 3915 by 521, we get 7 and a remainder of 268.
Use 7 as the next digit of our solution. 
Result so far: 7.0
Deduct 3647 from 3915 and we're left with 268.
Fetch the next digit (1) from the dividend, attach it to 268 and continue: 2681 / 521

Let's proceed to step 5:
2681 divided by 521 is 5 with a remainder of 76.
The next digit of our result is 5. 
Result so far: 75.0
If we subtract 2605 from 2681, we get 76.
Fetch the next digit (5) from the dividend, attach it to 76 and continue: 765 / 521

Moving on to step 6:
521 goes into 765 1 times with a remainder of 244.
The next digit of our result is 1. 
Result so far: 751.0
Deduct 521 from 765 and we're left with 244.
Bring next digit (9) of the dividend behind the 244 and repeat the process: 2449 / 521

Let's proceed to step 7:
521 can be fit into 2449 4 times, resulting in a remainder of 365.
The number 4 becomes the next digit in our result. 
Result so far: 7514.0
Deduct 2084 from 2449 and we're left with 365.
Fetch the next digit (8) from the dividend, attach it to 365 and continue: 3658 / 521

Moving on to step 8:
When dividing 3658 by 521, we get 7 with a remainder of 11.
Record the quotient 7 as the next digit in the result. 
Result so far: 75147.0
If we subtract 3647 from 3658, we get 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

On to step 9:
If we divide 110 by 521, we get 0 and a remainder of 110.
Use 0 as the next digit of our solution. 
Result so far: 75147.0
Subtract 0 from 110 to get 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1100, and continue the process.

On to step 10:
When dividing 1100 by 521, we get 2 with a remainder of 58.
Put 2 as the next digit of the answer. 
Result so far: 75147.02
The remainder is 58 after subtracting 1042 from 1100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 580, and continue the process.

Advancing to step 11:
The number 521 fits into 580 1 times, leaving a remainder of 59.
Put 1 as the next digit of the answer. 
Result so far: 75147.021
Subtract 521 from 580 to get 59.
Since there are no more digits in the dividend, we add a zero to the remainder making it 590, and continue the process.

On to step 12:
If we divide 590 by 521, we get 1 and a remainder of 69.
The number 1 becomes the next digit in our result. 
Result so far: 75147.0211
Subtract 521 from 590 to get 69.
Since there are no more digits in the dividend, we add a zero to the remainder making it 690, and continue the process.

The final result is 75147.0211 with a remainder of 0.00069.