We divide 43541540 by 421
The aim is to understand the frequency of 421 in 43541540.

Step 1:
The number 421 fits into 4 0 times, leaving a remainder of 4.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 4, we get 4.
Append the next digit (3) from the dividend to 4 and continue with: 43 / 421

Moving on to step 2:
When dividing 43 by 421, we get 0 with a remainder of 43.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 43, we end up with 43.
Take the next digit (5) from the dividend and append it to 43, then repeat: 435 / 421

On to step 3:
421 goes into 435 1 times with a remainder of 14.
Write down 1 as next digit of the result. 
Result so far: 1.0
Subtract 421 from 435 to get 14.
Fetch the next digit (4) from the dividend, attach it to 14 and continue: 144 / 421

On to step 4:
421 goes into 144 0 times with a remainder of 144.
The number 0 becomes the next digit in our result. 
Result so far: 10.0
The remainder is 144 after subtracting 0 from 144.
Fetch the next digit (1) from the dividend, attach it to 144 and continue: 1441 / 421

Advancing to step 5:
If we divide 1441 by 421, we get 3 and a remainder of 178.
The next digit of our result is 3. 
Result so far: 103.0
Subtract 1263 from 1441 to get 178.
Fetch the next digit (5) from the dividend, attach it to 178 and continue: 1785 / 421

Advancing to step 6:
The number 421 fits into 1785 4 times, leaving a remainder of 101.
The next digit of our result is 4. 
Result so far: 1034.0
Subtracting 1684 from 1785 leaves us with 101.
Append the next digit (4) from the dividend to 101 and continue with: 1014 / 421

Moving on to step 7:
If we divide 1014 by 421, we get 2 and a remainder of 172.
The number 2 becomes the next digit in our result. 
Result so far: 10342.0
Deduct 842 from 1014 and we're left with 172.
Fetch the next digit (0) from the dividend, attach it to 172 and continue: 1720 / 421

Let's proceed to step 8:
The number 421 fits into 1720 4 times, leaving a remainder of 36.
The next digit of our result is 4. 
Result so far: 103424.0
The remainder is 36 after subtracting 1684 from 1720.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

Going ahead to step 9:
360 divided by 421 is 0 with a remainder of 360.
Use 0 as the next digit of our solution. 
Result so far: 103424.0
Subtracting 0 from 360 leaves us with 360.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3600, and continue the process.

Going ahead to step 10:
When dividing 3600 by 421, we get 8 with a remainder of 232.
Write down 8 as next digit of the result. 
Result so far: 103424.08
If we take 3368 away from 3600, we end up with 232.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2320, and continue the process.

Going ahead to step 11:
The number 421 fits into 2320 5 times, leaving a remainder of 215.
Put 5 as the next digit of the answer. 
Result so far: 103424.085
If we subtract 2105 from 2320, we get 215.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2150, and continue the process.

Step 12:
If we divide 2150 by 421, we get 5 and a remainder of 45.
Write down 5 as next digit of the result. 
Result so far: 103424.0855
The remainder is 45 after subtracting 2105 from 2150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 450, and continue the process.

The final result is 103424.0855 with a remainder of 0.00045.