We look at the division of 816960 by 42 
The aim is to understand the frequency of 42 in 816960.

On to step 1:
42 goes into 8 0 times with a remainder of 8.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 8 leaves us with 8.
Grab the next digit (1) from the dividend, add it to 8, then carry on: 81 / 42

Moving on to step 2:
81 divided by 42 is 1 with a remainder of 39.
Put 1 as the next digit of the answer. 
Result so far: 1.0
If we subtract 42 from 81, we get 39.
Grab the next digit (6) from the dividend, add it to 39, then carry on: 396 / 42

On to step 3:
42 can be fit into 396 9 times, resulting in a remainder of 18.
The next digit of our result is 9. 
Result so far: 19.0
The remainder is 18 after subtracting 378 from 396.
Fetch the next digit (9) from the dividend, attach it to 18 and continue: 189 / 42

Step 4:
42 can be fit into 189 4 times, resulting in a remainder of 21.
The next digit of our result is 4. 
Result so far: 194.0
If we take 168 away from 189, we end up with 21.
Bring next digit (6) of the dividend behind the 21 and repeat the process: 216 / 42

Let's proceed to step 5:
42 goes into 216 5 times with a remainder of 6.
The number 5 becomes the next digit in our result. 
Result so far: 1945.0
Subtract 210 from 216 to get 6.
Bring next digit (0) of the dividend behind the 6 and repeat the process: 60 / 42

Going ahead to step 6:
If we divide 60 by 42, we get 1 and a remainder of 18.
The next digit of our result is 1. 
Result so far: 19451.0
If we subtract 42 from 60, we 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.

Let's proceed to step 7:
When dividing 180 by 42, we get 4 with a remainder of 12.
The number 4 becomes the next digit in our result. 
Result so far: 19451.4
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.

Going ahead to step 8:
120 divided by 42 is 2 with a remainder of 36.
The number 2 becomes the next digit in our result. 
Result so far: 19451.42
If we subtract 84 from 120, we 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.

Advancing to step 9:
42 can be fit into 360 8 times, resulting in a remainder of 24.
Write down 8 as next digit of the result. 
Result so far: 19451.428
The remainder is 24 after subtracting 336 from 360.
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 10:
The number 42 fits into 240 5 times, leaving a remainder of 30.
Write down 5 as next digit of the result. 
Result so far: 19451.4285
The remainder is 30 after subtracting 210 from 240.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Step 11:
42 goes into 300 7 times with a remainder of 6.
The number 7 becomes the next digit in our result. 
Result so far: 19451.42857
Deduct 294 from 300 and we're left 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 12:
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: 19451.428571
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.

Moving on to step 13:
42 goes into 180 4 times with a remainder of 12.
The number 4 becomes the next digit in our result. 
Result so far: 19451.4285714
If we take 168 away from 180, we end up with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

On to step 14:
42 goes into 120 2 times with a remainder of 36.
Record the quotient 2 as the next digit in the result. 
Result so far: 19451.42857142
If we take 84 away from 120, we end up with 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

The final result is 19451.42857142 with a remainder of 3.6e-08.