We look at the division of 400991 by 42 
The aim is to understand the frequency of 42 in 400991.

Advancing to step 1:
If we divide 4 by 42, we get 0 and a remainder of 4.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 4 leaves us with 4.
Grab the next digit (0) from the dividend, add it to 4, then carry on: 40 / 42

Let's proceed to step 2:
If we divide 40 by 42, we get 0 and a remainder of 40.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 40 to get 40.
Fetch the next digit (0) from the dividend, attach it to 40 and continue: 400 / 42

Let's proceed to step 3:
42 goes into 400 9 times with a remainder of 22.
Put 9 as the next digit of the answer. 
Result so far: 9.0
Subtracting 378 from 400 leaves us with 22.
Grab the next digit (9) from the dividend, add it to 22, then carry on: 229 / 42

On to step 4:
When dividing 229 by 42, we get 5 with a remainder of 19.
The next digit of our result is 5. 
Result so far: 95.0
The remainder is 19 after subtracting 210 from 229.
Append the next digit (9) from the dividend to 19 and continue with: 199 / 42

Step 5:
42 can be fit into 199 4 times, resulting in a remainder of 31.
The next digit of our result is 4. 
Result so far: 954.0
If we subtract 168 from 199, we get 31.
Bring next digit (1) of the dividend behind the 31 and repeat the process: 311 / 42

Advancing to step 6:
The number 42 fits into 311 7 times, leaving a remainder of 17.
Write down 7 as next digit of the result. 
Result so far: 9547.0
Deduct 294 from 311 and we're left with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

On to step 7:
42 can be fit into 170 4 times, resulting in a remainder of 2.
Record the quotient 4 as the next digit in the result. 
Result so far: 9547.4
Subtracting 168 from 170 leaves us with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Step 8:
When dividing 20 by 42, we get 0 with a remainder of 20.
Put 0 as the next digit of the answer. 
Result so far: 9547.4
Subtract 0 from 20 to get 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Going ahead to step 9:
The number 42 fits into 200 4 times, leaving a remainder of 32.
Put 4 as the next digit of the answer. 
Result so far: 9547.404
If we subtract 168 from 200, we get 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 10:
320 divided by 42 is 7 with a remainder of 26.
Use 7 as the next digit of our solution. 
Result so far: 9547.4047
Subtracting 294 from 320 leaves us with 26.
Since there are no more digits in the dividend, we add a zero to the remainder making it 260, and continue the process.

Step 11:
If we divide 260 by 42, we get 6 and a remainder of 8.
Record the quotient 6 as the next digit in the result. 
Result so far: 9547.40476
If we subtract 252 from 260, we get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Moving on to step 12:
The number 42 fits into 80 1 times, leaving a remainder of 38.
The next digit of our result is 1. 
Result so far: 9547.404761
The remainder is 38 after subtracting 42 from 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 380, and continue the process.

Let's proceed to step 13:
42 goes into 380 9 times with a remainder of 2.
Record the quotient 9 as the next digit in the result. 
Result so far: 9547.4047619
If we take 378 away from 380, we end up with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Moving on to step 14:
If we divide 20 by 42, we get 0 and a remainder of 20.
Write down 0 as next digit of the result. 
Result so far: 9547.4047619
Subtract 0 from 20 to get 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

In conclusion, the division gives 9547.4047619 with a balance of 2e-08.