17912453 ÷ 721 
The aim is to understand the frequency of 721 in 17912453.

Step 1:
When dividing 1 by 721, we get 0 with a remainder of 1.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 1 leaves us with 1.
Take the next digit (7) from the dividend and append it to 1, then repeat: 17 / 721

Step 2:
721 can be fit into 17 0 times, resulting in a remainder of 17.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 17, we get 17.
Fetch the next digit (9) from the dividend, attach it to 17 and continue: 179 / 721

Moving on to step 3:
721 goes into 179 0 times with a remainder of 179.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 179 and we're left with 179.
Fetch the next digit (1) from the dividend, attach it to 179 and continue: 1791 / 721

Moving on to step 4:
1791 divided by 721 is 2 with a remainder of 349.
Use 2 as the next digit of our solution. 
Result so far: 2.0
If we subtract 1442 from 1791, we get 349.
Bring next digit (2) of the dividend behind the 349 and repeat the process: 3492 / 721

Step 5:
The number 721 fits into 3492 4 times, leaving a remainder of 608.
The next digit of our result is 4. 
Result so far: 24.0
Subtract 2884 from 3492 to get 608.
Fetch the next digit (4) from the dividend, attach it to 608 and continue: 6084 / 721

On to step 6:
When dividing 6084 by 721, we get 8 with a remainder of 316.
Use 8 as the next digit of our solution. 
Result so far: 248.0
If we take 5768 away from 6084, we end up with 316.
Take the next digit (5) from the dividend and append it to 316, then repeat: 3165 / 721

Let's proceed to step 7:
721 can be fit into 3165 4 times, resulting in a remainder of 281.
Write down 4 as next digit of the result. 
Result so far: 2484.0
If we take 2884 away from 3165, we end up with 281.
Bring next digit (3) of the dividend behind the 281 and repeat the process: 2813 / 721

On to step 8:
The number 721 fits into 2813 3 times, leaving a remainder of 650.
The number 3 becomes the next digit in our result. 
Result so far: 24843.0
If we subtract 2163 from 2813, we get 650.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6500, and continue the process.

Step 9:
When dividing 6500 by 721, we get 9 with a remainder of 11.
Record the quotient 9 as the next digit in the result. 
Result so far: 24843.9
Subtracting 6489 from 6500 leaves us with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Let's proceed to step 10:
721 can be fit into 110 0 times, resulting in a remainder of 110.
Use 0 as the next digit of our solution. 
Result so far: 24843.9
Deduct 0 from 110 and we're left with 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1100, and continue the process.

Going ahead to step 11:
If we divide 1100 by 721, we get 1 and a remainder of 379.
Record the quotient 1 as the next digit in the result. 
Result so far: 24843.901
Subtracting 721 from 1100 leaves us with 379.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3790, and continue the process.

Step 12:
When dividing 3790 by 721, we get 5 with a remainder of 185.
Use 5 as the next digit of our solution. 
Result so far: 24843.9015
If we take 3605 away from 3790, we end up with 185.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1850, and continue the process.

Let's proceed to step 13:
If we divide 1850 by 721, we get 2 and a remainder of 408.
Write down 2 as next digit of the result. 
Result so far: 24843.90152
The remainder is 408 after subtracting 1442 from 1850.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4080, and continue the process.

Step 14:
721 goes into 4080 5 times with a remainder of 475.
Use 5 as the next digit of our solution. 
Result so far: 24843.901525
If we subtract 3605 from 4080, we get 475.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4750, and continue the process.

Let's proceed to step 15:
The number 721 fits into 4750 6 times, leaving a remainder of 424.
The number 6 becomes the next digit in our result. 
Result so far: 24843.9015256
Deduct 4326 from 4750 and we're left with 424.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4240, and continue the process.

Moving on to step 16:
721 can be fit into 4240 5 times, resulting in a remainder of 635.
The next digit of our result is 5. 
Result so far: 24843.90152565
Deduct 3605 from 4240 and we're left with 635.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6350, and continue the process.

The final outcome is 24843.90152565, with a leftover of 6.35e-07.