We're dividing 87938761 by 521 
The aim is to understand the frequency of 521 in 87938761.

Moving on to step 1:
8 divided by 521 is 0 with a remainder of 8.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 8 after subtracting 0 from 8.
Bring next digit (7) of the dividend behind the 8 and repeat the process: 87 / 521

Moving on to step 2:
521 can be fit into 87 0 times, resulting in a remainder of 87.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 87, we end up with 87.
Fetch the next digit (9) from the dividend, attach it to 87 and continue: 879 / 521

Step 3:
When dividing 879 by 521, we get 1 with a remainder of 358.
Put 1 as the next digit of the answer. 
Result so far: 1.0
The remainder is 358 after subtracting 521 from 879.
Bring next digit (3) of the dividend behind the 358 and repeat the process: 3583 / 521

Going ahead to step 4:
The number 521 fits into 3583 6 times, leaving a remainder of 457.
Write down 6 as next digit of the result. 
Result so far: 16.0
Deduct 3126 from 3583 and we're left with 457.
Bring next digit (8) of the dividend behind the 457 and repeat the process: 4578 / 521

Let's proceed to step 5:
4578 divided by 521 is 8 with a remainder of 410.
Write down 8 as next digit of the result. 
Result so far: 168.0
If we take 4168 away from 4578, we end up with 410.
Append the next digit (7) from the dividend to 410 and continue with: 4107 / 521

Step 6:
521 goes into 4107 7 times with a remainder of 460.
The number 7 becomes the next digit in our result. 
Result so far: 1687.0
If we subtract 3647 from 4107, we get 460.
Grab the next digit (6) from the dividend, add it to 460, then carry on: 4606 / 521

Going ahead to step 7:
521 can be fit into 4606 8 times, resulting in a remainder of 438.
Put 8 as the next digit of the answer. 
Result so far: 16878.0
Subtracting 4168 from 4606 leaves us with 438.
Fetch the next digit (1) from the dividend, attach it to 438 and continue: 4381 / 521

Going ahead to step 8:
The number 521 fits into 4381 8 times, leaving a remainder of 213.
Record the quotient 8 as the next digit in the result. 
Result so far: 168788.0
If we take 4168 away from 4381, we end up with 213.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2130, and continue the process.

Let's proceed to step 9:
The number 521 fits into 2130 4 times, leaving a remainder of 46.
Put 4 as the next digit of the answer. 
Result so far: 168788.4
Subtracting 2084 from 2130 leaves us with 46.
Since there are no more digits in the dividend, we add a zero to the remainder making it 460, and continue the process.

Moving on to step 10:
521 can be fit into 460 0 times, resulting in a remainder of 460.
The number 0 becomes the next digit in our result. 
Result so far: 168788.4
Deduct 0 from 460 and we're left with 460.
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:
The number 521 fits into 4600 8 times, leaving a remainder of 432.
Put 8 as the next digit of the answer. 
Result so far: 168788.408
The remainder is 432 after subtracting 4168 from 4600.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4320, and continue the process.

On to step 12:
521 goes into 4320 8 times with a remainder of 152.
Record the quotient 8 as the next digit in the result. 
Result so far: 168788.4088
Subtracting 4168 from 4320 leaves us with 152.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1520, and continue the process.

The final outcome is 168788.4088, with a leftover of 0.00152.