We look at the division of 41392395 by 645 
The aim is to understand the frequency of 645 in 41392395.

Moving on to step 1:
645 goes into 4 0 times with a remainder of 4.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 4 and we're left with 4.
Append the next digit (1) from the dividend to 4 and continue with: 41 / 645

Going ahead to step 2:
If we divide 41 by 645, we get 0 and a remainder of 41.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 41 leaves us with 41.
Take the next digit (3) from the dividend and append it to 41, then repeat: 413 / 645

Step 3:
645 goes into 413 0 times with a remainder of 413.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 413 leaves us with 413.
Include the next digit (9) from the dividend after 413, then repeat: 4139 / 645

Going ahead to step 4:
The number 645 fits into 4139 6 times, leaving a remainder of 269.
Write down 6 as next digit of the result. 
Result so far: 6.0
Subtracting 3870 from 4139 leaves us with 269.
Bring next digit (2) of the dividend behind the 269 and repeat the process: 2692 / 645

Moving on to step 5:
2692 divided by 645 is 4 with a remainder of 112.
Use 4 as the next digit of our solution. 
Result so far: 64.0
If we take 2580 away from 2692, we end up with 112.
Append the next digit (3) from the dividend to 112 and continue with: 1123 / 645

On to step 6:
If we divide 1123 by 645, we get 1 and a remainder of 478.
The number 1 becomes the next digit in our result. 
Result so far: 641.0
Subtracting 645 from 1123 leaves us with 478.
Fetch the next digit (9) from the dividend, attach it to 478 and continue: 4789 / 645

Step 7:
645 goes into 4789 7 times with a remainder of 274.
Record the quotient 7 as the next digit in the result. 
Result so far: 6417.0
Deduct 4515 from 4789 and we're left with 274.
Take the next digit (5) from the dividend and append it to 274, then repeat: 2745 / 645

Let's proceed to step 8:
The number 645 fits into 2745 4 times, leaving a remainder of 165.
The number 4 becomes the next digit in our result. 
Result so far: 64174.0
If we subtract 2580 from 2745, we get 165.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1650, and continue the process.

Step 9:
645 goes into 1650 2 times with a remainder of 360.
The next digit of our result is 2. 
Result so far: 64174.2
If we subtract 1290 from 1650, we get 360.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3600, and continue the process.

Advancing to step 10:
645 can be fit into 3600 5 times, resulting in a remainder of 375.
Put 5 as the next digit of the answer. 
Result so far: 64174.25
Deduct 3225 from 3600 and we're left with 375.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3750, and continue the process.

Moving on to step 11:
645 goes into 3750 5 times with a remainder of 525.
The number 5 becomes the next digit in our result. 
Result so far: 64174.255
Subtracting 3225 from 3750 leaves us with 525.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5250, and continue the process.

The final result is 64174.255 with a remainder of 0.0525.