We look at the division of 99806989 by 421 
The aim is to understand the frequency of 421 in 99806989.

Let's proceed to step 1:
421 goes into 9 0 times with a remainder of 9.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 9 leaves us with 9.
Fetch the next digit (9) from the dividend, attach it to 9 and continue: 99 / 421

Step 2:
421 goes into 99 0 times with a remainder of 99.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 99 to get 99.
Append the next digit (8) from the dividend to 99 and continue with: 998 / 421

Going ahead to step 3:
998 divided by 421 is 2 with a remainder of 156.
Use 2 as the next digit of our solution. 
Result so far: 2.0
Deduct 842 from 998 and we're left with 156.
Take the next digit (0) from the dividend and append it to 156, then repeat: 1560 / 421

Moving on to step 4:
421 can be fit into 1560 3 times, resulting in a remainder of 297.
The number 3 becomes the next digit in our result. 
Result so far: 23.0
If we subtract 1263 from 1560, we get 297.
Take the next digit (6) from the dividend and append it to 297, then repeat: 2976 / 421

Step 5:
421 can be fit into 2976 7 times, resulting in a remainder of 29.
Write down 7 as next digit of the result. 
Result so far: 237.0
If we subtract 2947 from 2976, we get 29.
Grab the next digit (9) from the dividend, add it to 29, then carry on: 299 / 421

Advancing to step 6:
If we divide 299 by 421, we get 0 and a remainder of 299.
Put 0 as the next digit of the answer. 
Result so far: 2370.0
Subtract 0 from 299 to get 299.
Grab the next digit (8) from the dividend, add it to 299, then carry on: 2998 / 421

Moving on to step 7:
2998 divided by 421 is 7 with a remainder of 51.
The next digit of our result is 7. 
Result so far: 23707.0
If we take 2947 away from 2998, we end up with 51.
Bring next digit (9) of the dividend behind the 51 and repeat the process: 519 / 421

Going ahead to step 8:
The number 421 fits into 519 1 times, leaving a remainder of 98.
The number 1 becomes the next digit in our result. 
Result so far: 237071.0
If we subtract 421 from 519, we get 98.
Since there are no more digits in the dividend, we add a zero to the remainder making it 980, and continue the process.

Step 9:
421 can be fit into 980 2 times, resulting in a remainder of 138.
Write down 2 as next digit of the result. 
Result so far: 237071.2
Subtract 842 from 980 to get 138.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1380, and continue the process.

Step 10:
1380 divided by 421 is 3 with a remainder of 117.
Use 3 as the next digit of our solution. 
Result so far: 237071.23
Subtract 1263 from 1380 to get 117.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1170, and continue the process.

Moving on to step 11:
When dividing 1170 by 421, we get 2 with a remainder of 328.
Put 2 as the next digit of the answer. 
Result so far: 237071.232
If we take 842 away from 1170, we end up with 328.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3280, and continue the process.

Step 12:
When dividing 3280 by 421, we get 7 with a remainder of 333.
Record the quotient 7 as the next digit in the result. 
Result so far: 237071.2327
The remainder is 333 after subtracting 2947 from 3280.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3330, and continue the process.

Moving on to step 13:
421 can be fit into 3330 7 times, resulting in a remainder of 383.
The number 7 becomes the next digit in our result. 
Result so far: 237071.23277
If we take 2947 away from 3330, we end up with 383.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3830, and continue the process.

The quotient of the division is 237071.23277, and the remainder is 0.000383.