90431094 divided by 991 
The aim is to understand the frequency of 991 in 90431094.

Step 1:
9 divided by 991 is 0 with a remainder of 9.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 9, we get 9.
Include the next digit (0) from the dividend after 9, then repeat: 90 / 991

Let's proceed to step 2:
If we divide 90 by 991, we get 0 and a remainder of 90.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 90 leaves us with 90.
Append the next digit (4) from the dividend to 90 and continue with: 904 / 991

Moving on to step 3:
991 goes into 904 0 times with a remainder of 904.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 904, we end up with 904.
Include the next digit (3) from the dividend after 904, then repeat: 9043 / 991

On to step 4:
991 can be fit into 9043 9 times, resulting in a remainder of 124.
Record the quotient 9 as the next digit in the result. 
Result so far: 9.0
Subtract 8919 from 9043 to get 124.
Append the next digit (1) from the dividend to 124 and continue with: 1241 / 991

Moving on to step 5:
991 can be fit into 1241 1 times, resulting in a remainder of 250.
Use 1 as the next digit of our solution. 
Result so far: 91.0
The remainder is 250 after subtracting 991 from 1241.
Fetch the next digit (0) from the dividend, attach it to 250 and continue: 2500 / 991

Step 6:
2500 divided by 991 is 2 with a remainder of 518.
Put 2 as the next digit of the answer. 
Result so far: 912.0
The remainder is 518 after subtracting 1982 from 2500.
Append the next digit (9) from the dividend to 518 and continue with: 5189 / 991

Going ahead to step 7:
The number 991 fits into 5189 5 times, leaving a remainder of 234.
The next digit of our result is 5. 
Result so far: 9125.0
If we subtract 4955 from 5189, we get 234.
Fetch the next digit (4) from the dividend, attach it to 234 and continue: 2344 / 991

On to step 8:
The number 991 fits into 2344 2 times, leaving a remainder of 362.
The number 2 becomes the next digit in our result. 
Result so far: 91252.0
If we subtract 1982 from 2344, we get 362.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3620, and continue the process.

Advancing to step 9:
When dividing 3620 by 991, we get 3 with a remainder of 647.
The number 3 becomes the next digit in our result. 
Result so far: 91252.3
If we subtract 2973 from 3620, we get 647.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6470, and continue the process.

Going ahead to step 10:
6470 divided by 991 is 6 with a remainder of 524.
Use 6 as the next digit of our solution. 
Result so far: 91252.36
If we subtract 5946 from 6470, we get 524.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5240, and continue the process.

Advancing to step 11:
5240 divided by 991 is 5 with a remainder of 285.
The number 5 becomes the next digit in our result. 
Result so far: 91252.365
Deduct 4955 from 5240 and we're left with 285.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2850, and continue the process.

Advancing to step 12:
2850 divided by 991 is 2 with a remainder of 868.
Put 2 as the next digit of the answer. 
Result so far: 91252.3652
If we take 1982 away from 2850, we end up with 868.
Since there are no more digits in the dividend, we add a zero to the remainder making it 8680, and continue the process.

Moving on to step 13:
991 can be fit into 8680 8 times, resulting in a remainder of 752.
The number 8 becomes the next digit in our result. 
Result so far: 91252.36528
The remainder is 752 after subtracting 7928 from 8680.
Since there are no more digits in the dividend, we add a zero to the remainder making it 7520, and continue the process.

Let's proceed to step 14:
When dividing 7520 by 991, we get 7 with a remainder of 583.
Use 7 as the next digit of our solution. 
Result so far: 91252.365287
The remainder is 583 after subtracting 6937 from 7520.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5830, and continue the process.

Let's proceed to step 15:
991 goes into 5830 5 times with a remainder of 875.
The next digit of our result is 5. 
Result so far: 91252.3652875
If we take 4955 away from 5830, we end up with 875.
Since there are no more digits in the dividend, we add a zero to the remainder making it 8750, and continue the process.

Advancing to step 16:
If we divide 8750 by 991, we get 8 and a remainder of 822.
The number 8 becomes the next digit in our result. 
Result so far: 91252.36528758
If we subtract 7928 from 8750, we get 822.
Since there are no more digits in the dividend, we add a zero to the remainder making it 8220, and continue the process.

The final result is 91252.36528758 with a remainder of 8.22e-07.