We look at the division of 421671 by 42 
The aim is to understand the frequency of 42 in 421671.

Let's proceed to step 1:
42 can be fit into 4 0 times, resulting in a remainder of 4.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 4 to get 4.
Grab the next digit (2) from the dividend, add it to 4, then carry on: 42 / 42

Step 2:
42 can be fit into 42 1 times, resulting in a remainder of 0.
Write down 1 as next digit of the result. 
Result so far: 1.0
Subtracting 42 from 42 leaves us with 0.
Fetch the next digit (1) from the dividend, attach it to 0 and continue: 1 / 42

Moving on to step 3:
42 can be fit into 1 0 times, resulting in a remainder of 1.
The number 0 becomes the next digit in our result. 
Result so far: 10.0
The remainder is 1 after subtracting 0 from 1.
Append the next digit (6) from the dividend to 1 and continue with: 16 / 42

Let's proceed to step 4:
When dividing 16 by 42, we get 0 with a remainder of 16.
Use 0 as the next digit of our solution. 
Result so far: 100.0
Subtract 0 from 16 to get 16.
Include the next digit (7) from the dividend after 16, then repeat: 167 / 42

On to step 5:
42 can be fit into 167 3 times, resulting in a remainder of 41.
The next digit of our result is 3. 
Result so far: 1003.0
The remainder is 41 after subtracting 126 from 167.
Include the next digit (1) from the dividend after 41, then repeat: 411 / 42

Moving on to step 6:
When dividing 411 by 42, we get 9 with a remainder of 33.
Use 9 as the next digit of our solution. 
Result so far: 10039.0
Subtract 378 from 411 to get 33.
Since there are no more digits in the dividend, we add a zero to the remainder making it 330, and continue the process.

Going ahead to step 7:
330 divided by 42 is 7 with a remainder of 36.
Use 7 as the next digit of our solution. 
Result so far: 10039.7
Subtract 294 from 330 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.

Step 8:
42 goes into 360 8 times with a remainder of 24.
Use 8 as the next digit of our solution. 
Result so far: 10039.78
Deduct 336 from 360 and we're left 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.

Going ahead to step 9:
42 goes into 240 5 times with a remainder of 30.
Put 5 as the next digit of the answer. 
Result so far: 10039.785
Deduct 210 from 240 and we're left with 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Advancing to step 10:
300 divided by 42 is 7 with a remainder of 6.
Write down 7 as next digit of the result. 
Result so far: 10039.7857
Subtract 294 from 300 to get 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 11:
42 can be fit into 60 1 times, resulting in a remainder of 18.
Use 1 as the next digit of our solution. 
Result so far: 10039.78571
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.

Step 12:
The number 42 fits into 180 4 times, leaving a remainder of 12.
Put 4 as the next digit of the answer. 
Result so far: 10039.785714
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.

Going ahead to step 13:
If we divide 120 by 42, we get 2 and a remainder of 36.
Write down 2 as next digit of the result. 
Result so far: 10039.7857142
Deduct 84 from 120 and we're left 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.

Advancing to step 14:
360 divided by 42 is 8 with a remainder of 24.
The next digit of our result is 8. 
Result so far: 10039.78571428
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.

The quotient of the division is 10039.78571428, and the remainder is 2.4e-08.