We look at the division of 513488 by 25 
The aim is to understand the frequency of 25 in 513488.

Step 1:
When dividing 5 by 25, we get 0 with a remainder of 5.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 5, we end up with 5.
Include the next digit (1) from the dividend after 5, then repeat: 51 / 25

Moving on to step 2:
25 can be fit into 51 2 times, resulting in a remainder of 1.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
Subtracting 50 from 51 leaves us with 1.
Grab the next digit (3) from the dividend, add it to 1, then carry on: 13 / 25

Step 3:
If we divide 13 by 25, we get 0 and a remainder of 13.
The next digit of our result is 0. 
Result so far: 20.0
Subtract 0 from 13 to get 13.
Grab the next digit (4) from the dividend, add it to 13, then carry on: 134 / 25

Step 4:
The number 25 fits into 134 5 times, leaving a remainder of 9.
The next digit of our result is 5. 
Result so far: 205.0
If we subtract 125 from 134, we get 9.
Take the next digit (8) from the dividend and append it to 9, then repeat: 98 / 25

Advancing to step 5:
When dividing 98 by 25, we get 3 with a remainder of 23.
The number 3 becomes the next digit in our result. 
Result so far: 2053.0
If we take 75 away from 98, we end up with 23.
Bring next digit (8) of the dividend behind the 23 and repeat the process: 238 / 25

Advancing to step 6:
25 can be fit into 238 9 times, resulting in a remainder of 13.
Put 9 as the next digit of the answer. 
Result so far: 20539.0
Subtract 225 from 238 to get 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

On to step 7:
130 divided by 25 is 5 with a remainder of 5.
Record the quotient 5 as the next digit in the result. 
Result so far: 20539.5
Subtract 125 from 130 to get 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Moving on to step 8:
The number 25 fits into 50 2 times, leaving a remainder of 0.
Record the quotient 2 as the next digit in the result. 
Result so far: 20539.52
Deduct 50 from 50 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Let's proceed to step 9:
When dividing 0 by 25, we get 0 with a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 20539.52
If we take 0 away from 0, we end up with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Step 10:
25 goes into 0 0 times with a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 20539.52
The remainder is 0 after subtracting 0 from 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final result is 20539.52 with a remainder of 0.0.