We look at the division of 577504 by 87 
The aim is to understand the frequency of 87 in 577504.

On to step 1:
The number 87 fits into 5 0 times, leaving a remainder of 5.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Append the next digit (7) from the dividend to 5 and continue with: 57 / 87

Going ahead to step 2:
87 can be fit into 57 0 times, resulting in a remainder of 57.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 57, we get 57.
Append the next digit (7) from the dividend to 57 and continue with: 577 / 87

Let's proceed to step 3:
When dividing 577 by 87, we get 6 with a remainder of 55.
Use 6 as the next digit of our solution. 
Result so far: 6.0
Subtract 522 from 577 to get 55.
Fetch the next digit (5) from the dividend, attach it to 55 and continue: 555 / 87

Advancing to step 4:
87 can be fit into 555 6 times, resulting in a remainder of 33.
The number 6 becomes the next digit in our result. 
Result so far: 66.0
Deduct 522 from 555 and we're left with 33.
Bring next digit (0) of the dividend behind the 33 and repeat the process: 330 / 87

Step 5:
330 divided by 87 is 3 with a remainder of 69.
The next digit of our result is 3. 
Result so far: 663.0
Subtract 261 from 330 to get 69.
Append the next digit (4) from the dividend to 69 and continue with: 694 / 87

Going ahead to step 6:
The number 87 fits into 694 7 times, leaving a remainder of 85.
Use 7 as the next digit of our solution. 
Result so far: 6637.0
Subtract 609 from 694 to get 85.
Since there are no more digits in the dividend, we add a zero to the remainder making it 850, and continue the process.

Step 7:
87 can be fit into 850 9 times, resulting in a remainder of 67.
Record the quotient 9 as the next digit in the result. 
Result so far: 6637.9
Subtracting 783 from 850 leaves us with 67.
Since there are no more digits in the dividend, we add a zero to the remainder making it 670, and continue the process.

Going ahead to step 8:
When dividing 670 by 87, we get 7 with a remainder of 61.
The number 7 becomes the next digit in our result. 
Result so far: 6637.97
Subtract 609 from 670 to get 61.
Since there are no more digits in the dividend, we add a zero to the remainder making it 610, and continue the process.

Step 9:
When dividing 610 by 87, we get 7 with a remainder of 1.
Put 7 as the next digit of the answer. 
Result so far: 6637.977
If we take 609 away from 610, we end up with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

After the division, we end up with 6637.977 and a remainder of 0.0001.