We look at the division of 413490 by 25 
The aim is to understand the frequency of 25 in 413490.

Step 1:
When dividing 4 by 25, we get 0 with a remainder of 4.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 4, we get 4.
Take the next digit (1) from the dividend and append it to 4, then repeat: 41 / 25

Advancing to step 2:
The number 25 fits into 41 1 times, leaving a remainder of 16.
Write down 1 as next digit of the result. 
Result so far: 1.0
If we take 25 away from 41, we end up with 16.
Fetch the next digit (3) from the dividend, attach it to 16 and continue: 163 / 25

On to step 3:
If we divide 163 by 25, we get 6 and a remainder of 13.
Put 6 as the next digit of the answer. 
Result so far: 16.0
If we subtract 150 from 163, we get 13.
Append the next digit (4) from the dividend to 13 and continue with: 134 / 25

Let's proceed to step 4:
The number 25 fits into 134 5 times, leaving a remainder of 9.
Write down 5 as next digit of the result. 
Result so far: 165.0
The remainder is 9 after subtracting 125 from 134.
Append the next digit (9) from the dividend to 9 and continue with: 99 / 25

Moving on to step 5:
25 can be fit into 99 3 times, resulting in a remainder of 24.
Put 3 as the next digit of the answer. 
Result so far: 1653.0
The remainder is 24 after subtracting 75 from 99.
Grab the next digit (0) from the dividend, add it to 24, then carry on: 240 / 25

Going ahead to step 6:
If we divide 240 by 25, we get 9 and a remainder of 15.
Record the quotient 9 as the next digit in the result. 
Result so far: 16539.0
If we subtract 225 from 240, we get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

On to step 7:
150 divided by 25 is 6 with a remainder of 0.
The next digit of our result is 6. 
Result so far: 16539.6
Subtracting 150 from 150 leaves us 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.

Going ahead to step 8:
The number 25 fits into 0 0 times, leaving a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 16539.6
Subtract 0 from 0 to 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.

Advancing to step 9:
If we divide 0 by 25, we get 0 and a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 16539.6
Subtract 0 from 0 to 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.

The final result is 16539.6 with a remainder of 0.0.