We're dividing 663871 by 25 
The aim is to understand the frequency of 25 in 663871.

On to step 1:
6 divided by 25 is 0 with a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 6 to get 6.
Fetch the next digit (6) from the dividend, attach it to 6 and continue: 66 / 25

Advancing to step 2:
25 can be fit into 66 2 times, resulting in a remainder of 16.
Record the quotient 2 as the next digit in the result. 
Result so far: 2.0
Deduct 50 from 66 and we're left with 16.
Take the next digit (3) from the dividend and append it to 16, then repeat: 163 / 25

Going ahead to step 3:
The number 25 fits into 163 6 times, leaving a remainder of 13.
Use 6 as the next digit of our solution. 
Result so far: 26.0
Deduct 150 from 163 and we're left with 13.
Include the next digit (8) from the dividend after 13, then repeat: 138 / 25

On to step 4:
138 divided by 25 is 5 with a remainder of 13.
The number 5 becomes the next digit in our result. 
Result so far: 265.0
Subtract 125 from 138 to get 13.
Grab the next digit (7) from the dividend, add it to 13, then carry on: 137 / 25

Step 5:
25 can be fit into 137 5 times, resulting in a remainder of 12.
Use 5 as the next digit of our solution. 
Result so far: 2655.0
Subtracting 125 from 137 leaves us with 12.
Include the next digit (1) from the dividend after 12, then repeat: 121 / 25

Let's proceed to step 6:
25 can be fit into 121 4 times, resulting in a remainder of 21.
Write down 4 as next digit of the result. 
Result so far: 26554.0
If we subtract 100 from 121, we get 21.
Since there are no more digits in the dividend, we add a zero to the remainder making it 210, and continue the process.

Going ahead to step 7:
When dividing 210 by 25, we get 8 with a remainder of 10.
Use 8 as the next digit of our solution. 
Result so far: 26554.8
Subtracting 200 from 210 leaves us 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.

On to step 8:
When dividing 100 by 25, we get 4 with a remainder of 0.
Use 4 as the next digit of our solution. 
Result so far: 26554.84
The remainder is 0 after subtracting 100 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Moving on to step 9:
When dividing 0 by 25, we get 0 with a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 26554.84
If we subtract 0 from 0, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Moving on to step 10:
The number 25 fits into 0 0 times, leaving a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 26554.84
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 26554.84 with a remainder of 0.0.