We're dividing 521509 by 78 
The aim is to understand the frequency of 78 in 521509.

Step 1:
The number 78 fits into 5 0 times, leaving a remainder of 5.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 5, we get 5.
Include the next digit (2) from the dividend after 5, then repeat: 52 / 78

Step 2:
The number 78 fits into 52 0 times, leaving a remainder of 52.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 52, we end up with 52.
Take the next digit (1) from the dividend and append it to 52, then repeat: 521 / 78

Advancing to step 3:
521 divided by 78 is 6 with a remainder of 53.
The number 6 becomes the next digit in our result. 
Result so far: 6.0
Subtract 468 from 521 to get 53.
Include the next digit (5) from the dividend after 53, then repeat: 535 / 78

Let's proceed to step 4:
If we divide 535 by 78, we get 6 and a remainder of 67.
Write down 6 as next digit of the result. 
Result so far: 66.0
Deduct 468 from 535 and we're left with 67.
Bring next digit (0) of the dividend behind the 67 and repeat the process: 670 / 78

Moving on to step 5:
The number 78 fits into 670 8 times, leaving a remainder of 46.
Write down 8 as next digit of the result. 
Result so far: 668.0
If we take 624 away from 670, we end up with 46.
Append the next digit (9) from the dividend to 46 and continue with: 469 / 78

Going ahead to step 6:
78 goes into 469 6 times with a remainder of 1.
The number 6 becomes the next digit in our result. 
Result so far: 6686.0
Subtracting 468 from 469 leaves us 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.

Going ahead to step 7:
78 can be fit into 10 0 times, resulting in a remainder of 10.
The next digit of our result is 0. 
Result so far: 6686.0
If we take 0 away from 10, we end up with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 8:
If we divide 100 by 78, we get 1 and a remainder of 22.
The next digit of our result is 1. 
Result so far: 6686.01
Subtracting 78 from 100 leaves us with 22.
Since there are no more digits in the dividend, we add a zero to the remainder making it 220, and continue the process.

Step 9:
When dividing 220 by 78, we get 2 with a remainder of 64.
Write down 2 as next digit of the result. 
Result so far: 6686.012
Subtract 156 from 220 to get 64.
Since there are no more digits in the dividend, we add a zero to the remainder making it 640, and continue the process.

On to step 10:
78 can be fit into 640 8 times, resulting in a remainder of 16.
Use 8 as the next digit of our solution. 
Result so far: 6686.0128
The remainder is 16 after subtracting 624 from 640.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Moving on to step 11:
The number 78 fits into 160 2 times, leaving a remainder of 4.
Write down 2 as next digit of the result. 
Result so far: 6686.01282
Subtract 156 from 160 to get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

On to step 12:
40 divided by 78 is 0 with a remainder of 40.
Use 0 as the next digit of our solution. 
Result so far: 6686.01282
The remainder is 40 after subtracting 0 from 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

Advancing to step 13:
78 can be fit into 400 5 times, resulting in a remainder of 10.
The number 5 becomes the next digit in our result. 
Result so far: 6686.0128205
If we subtract 390 from 400, we get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Going ahead to step 14:
78 goes into 100 1 times with a remainder of 22.
Use 1 as the next digit of our solution. 
Result so far: 6686.01282051
Subtracting 78 from 100 leaves us with 22.
Since there are no more digits in the dividend, we add a zero to the remainder making it 220, and continue the process.

In conclusion, the division gives 6686.01282051 with a balance of 2.2e-08.