We look at the division of 664596 by 42 
The aim is to understand the frequency of 42 in 664596.

On to step 1:
The number 42 fits into 6 0 times, leaving a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Append the next digit (6) from the dividend to 6 and continue with: 66 / 42

Advancing to step 2:
If we divide 66 by 42, we get 1 and a remainder of 24.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Subtract 42 from 66 to get 24.
Append the next digit (4) from the dividend to 24 and continue with: 244 / 42

Going ahead to step 3:
When dividing 244 by 42, we get 5 with a remainder of 34.
Use 5 as the next digit of our solution. 
Result so far: 15.0
If we take 210 away from 244, we end up with 34.
Bring next digit (5) of the dividend behind the 34 and repeat the process: 345 / 42

Moving on to step 4:
When dividing 345 by 42, we get 8 with a remainder of 9.
The number 8 becomes the next digit in our result. 
Result so far: 158.0
The remainder is 9 after subtracting 336 from 345.
Append the next digit (9) from the dividend to 9 and continue with: 99 / 42

Let's proceed to step 5:
42 can be fit into 99 2 times, resulting in a remainder of 15.
Put 2 as the next digit of the answer. 
Result so far: 1582.0
If we subtract 84 from 99, we get 15.
Grab the next digit (6) from the dividend, add it to 15, then carry on: 156 / 42

Advancing to step 6:
The number 42 fits into 156 3 times, leaving a remainder of 30.
Write down 3 as next digit of the result. 
Result so far: 15823.0
If we subtract 126 from 156, we get 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Let's proceed to step 7:
42 can be fit into 300 7 times, resulting in a remainder of 6.
The number 7 becomes the next digit in our result. 
Result so far: 15823.7
Subtracting 294 from 300 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.

Moving on to step 8:
The number 42 fits into 60 1 times, leaving a remainder of 18.
Use 1 as the next digit of our solution. 
Result so far: 15823.71
If we take 42 away from 60, we end up with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Step 9:
When dividing 180 by 42, we get 4 with a remainder of 12.
Use 4 as the next digit of our solution. 
Result so far: 15823.714
Subtract 168 from 180 to get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Advancing to step 10:
The number 42 fits into 120 2 times, leaving a remainder of 36.
Use 2 as the next digit of our solution. 
Result so far: 15823.7142
Subtract 84 from 120 to get 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

Let's proceed to step 11:
When dividing 360 by 42, we get 8 with a remainder of 24.
Write down 8 as next digit of the result. 
Result so far: 15823.71428
If we take 336 away from 360, we end up with 24.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

Let's proceed to step 12:
The number 42 fits into 240 5 times, leaving a remainder of 30.
The next digit of our result is 5. 
Result so far: 15823.714285
If we subtract 210 from 240, we get 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Going ahead to step 13:
If we divide 300 by 42, we get 7 and a remainder of 6.
Record the quotient 7 as the next digit in the result. 
Result so far: 15823.7142857
Subtracting 294 from 300 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 14:
42 goes into 60 1 times with a remainder of 18.
Record the quotient 1 as the next digit in the result. 
Result so far: 15823.71428571
Subtract 42 from 60 to get 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

After the division, we end up with 15823.71428571 and a remainder of 1.8e-08.