We look at the division of 666438 by 64 
The aim is to understand the frequency of 64 in 666438.

Step 1:
When dividing 6 by 64, we get 0 with a remainder of 6.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 6 to get 6.
Include the next digit (6) from the dividend after 6, then repeat: 66 / 64

Going ahead to step 2:
If we divide 66 by 64, we get 1 and a remainder of 2.
Write down 1 as next digit of the result. 
Result so far: 1.0
Subtract 64 from 66 to get 2.
Take the next digit (6) from the dividend and append it to 2, then repeat: 26 / 64

Advancing to step 3:
When dividing 26 by 64, we get 0 with a remainder of 26.
The number 0 becomes the next digit in our result. 
Result so far: 10.0
Deduct 0 from 26 and we're left with 26.
Include the next digit (4) from the dividend after 26, then repeat: 264 / 64

Step 4:
64 can be fit into 264 4 times, resulting in a remainder of 8.
The number 4 becomes the next digit in our result. 
Result so far: 104.0
Subtract 256 from 264 to get 8.
Include the next digit (3) from the dividend after 8, then repeat: 83 / 64

Going ahead to step 5:
64 goes into 83 1 times with a remainder of 19.
Record the quotient 1 as the next digit in the result. 
Result so far: 1041.0
If we take 64 away from 83, we end up with 19.
Take the next digit (8) from the dividend and append it to 19, then repeat: 198 / 64

Moving on to step 6:
64 can be fit into 198 3 times, resulting in a remainder of 6.
The next digit of our result is 3. 
Result so far: 10413.0
Subtracting 192 from 198 leaves us with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Going ahead to step 7:
64 goes into 60 0 times with a remainder of 60.
The next digit of our result is 0. 
Result so far: 10413.0
Subtract 0 from 60 to get 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

Let's proceed to step 8:
The number 64 fits into 600 9 times, leaving a remainder of 24.
The number 9 becomes the next digit in our result. 
Result so far: 10413.09
If we subtract 576 from 600, we get 24.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

Advancing to step 9:
The number 64 fits into 240 3 times, leaving a remainder of 48.
The next digit of our result is 3. 
Result so far: 10413.093
The remainder is 48 after subtracting 192 from 240.
Since there are no more digits in the dividend, we add a zero to the remainder making it 480, and continue the process.

Going ahead to step 10:
480 divided by 64 is 7 with a remainder of 32.
Put 7 as the next digit of the answer. 
Result so far: 10413.0937
If we take 448 away from 480, we end up with 32.
Since there are no more digits in the dividend, we add a zero to the remainder making it 320, and continue the process.

Going ahead to step 11:
320 divided by 64 is 5 with a remainder of 0.
Put 5 as the next digit of the answer. 
Result so far: 10413.09375
If we take 320 away from 320, 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.

On to step 12:
64 can be fit into 0 0 times, resulting in a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 10413.09375
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 13:
When dividing 0 by 64, we get 0 with a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 10413.09375
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 outcome is 10413.09375, with a leftover of 0.0.