We look at the division of 39051887 by 421 
The aim is to understand the frequency of 421 in 39051887.

Let's proceed to step 1:
The number 421 fits into 3 0 times, leaving a remainder of 3.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 3 after subtracting 0 from 3.
Append the next digit (9) from the dividend to 3 and continue with: 39 / 421

Step 2:
When dividing 39 by 421, we get 0 with a remainder of 39.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 39 leaves us with 39.
Bring next digit (0) of the dividend behind the 39 and repeat the process: 390 / 421

Moving on to step 3:
421 goes into 390 0 times with a remainder of 390.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 390 after subtracting 0 from 390.
Bring next digit (5) of the dividend behind the 390 and repeat the process: 3905 / 421

Step 4:
3905 divided by 421 is 9 with a remainder of 116.
Record the quotient 9 as the next digit in the result. 
Result so far: 9.0
Subtract 3789 from 3905 to get 116.
Grab the next digit (1) from the dividend, add it to 116, then carry on: 1161 / 421

Going ahead to step 5:
When dividing 1161 by 421, we get 2 with a remainder of 319.
Put 2 as the next digit of the answer. 
Result so far: 92.0
If we take 842 away from 1161, we end up with 319.
Fetch the next digit (8) from the dividend, attach it to 319 and continue: 3198 / 421

Going ahead to step 6:
3198 divided by 421 is 7 with a remainder of 251.
Put 7 as the next digit of the answer. 
Result so far: 927.0
Deduct 2947 from 3198 and we're left with 251.
Grab the next digit (8) from the dividend, add it to 251, then carry on: 2518 / 421

Advancing to step 7:
421 can be fit into 2518 5 times, resulting in a remainder of 413.
Put 5 as the next digit of the answer. 
Result so far: 9275.0
Subtracting 2105 from 2518 leaves us with 413.
Take the next digit (7) from the dividend and append it to 413, then repeat: 4137 / 421

Going ahead to step 8:
4137 divided by 421 is 9 with a remainder of 348.
The next digit of our result is 9. 
Result so far: 92759.0
Deduct 3789 from 4137 and we're left with 348.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3480, and continue the process.

Step 9:
If we divide 3480 by 421, we get 8 and a remainder of 112.
Put 8 as the next digit of the answer. 
Result so far: 92759.8
If we take 3368 away from 3480, we end up with 112.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1120, and continue the process.

Advancing to step 10:
The number 421 fits into 1120 2 times, leaving a remainder of 278.
Record the quotient 2 as the next digit in the result. 
Result so far: 92759.82
The remainder is 278 after subtracting 842 from 1120.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2780, and continue the process.

On to step 11:
The number 421 fits into 2780 6 times, leaving a remainder of 254.
Record the quotient 6 as the next digit in the result. 
Result so far: 92759.826
If we take 2526 away from 2780, we end up with 254.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2540, and continue the process.

Moving on to step 12:
When dividing 2540 by 421, we get 6 with a remainder of 14.
Record the quotient 6 as the next digit in the result. 
Result so far: 92759.8266
Deduct 2526 from 2540 and we're left with 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

The quotient of the division is 92759.8266, and the remainder is 0.00014.