We look at the division of 521435 by 42 
The aim is to understand the frequency of 42 in 521435.

Moving on to step 1:
5 divided by 42 is 0 with a remainder of 5.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 5 and we're left with 5.
Bring next digit (2) of the dividend behind the 5 and repeat the process: 52 / 42

Moving on to step 2:
If we divide 52 by 42, we get 1 and a remainder of 10.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Deduct 42 from 52 and we're left with 10.
Take the next digit (1) from the dividend and append it to 10, then repeat: 101 / 42

Let's proceed to step 3:
When dividing 101 by 42, we get 2 with a remainder of 17.
Record the quotient 2 as the next digit in the result. 
Result so far: 12.0
If we take 84 away from 101, we end up with 17.
Fetch the next digit (4) from the dividend, attach it to 17 and continue: 174 / 42

On to step 4:
174 divided by 42 is 4 with a remainder of 6.
The number 4 becomes the next digit in our result. 
Result so far: 124.0
If we subtract 168 from 174, we get 6.
Fetch the next digit (3) from the dividend, attach it to 6 and continue: 63 / 42

On to step 5:
63 divided by 42 is 1 with a remainder of 21.
Record the quotient 1 as the next digit in the result. 
Result so far: 1241.0
If we subtract 42 from 63, we get 21.
Include the next digit (5) from the dividend after 21, then repeat: 215 / 42

Moving on to step 6:
42 can be fit into 215 5 times, resulting in a remainder of 5.
The number 5 becomes the next digit in our result. 
Result so far: 12415.0
If we take 210 away from 215, we end up with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Moving on to step 7:
If we divide 50 by 42, we get 1 and a remainder of 8.
The number 1 becomes the next digit in our result. 
Result so far: 12415.1
Deduct 42 from 50 and we're left with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

On to step 8:
The number 42 fits into 80 1 times, leaving a remainder of 38.
Put 1 as the next digit of the answer. 
Result so far: 12415.11
If we take 42 away from 80, we end up with 38.
Since there are no more digits in the dividend, we add a zero to the remainder making it 380, and continue the process.

In conclusion, the division gives 12415.11 with a balance of 0.038.