We look at the division of 721648 by 73 
The aim is to understand the frequency of 73 in 721648.

Going ahead to step 1:
73 goes into 7 0 times with a remainder of 7.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 7 leaves us with 7.
Grab the next digit (2) from the dividend, add it to 7, then carry on: 72 / 73

Step 2:
When dividing 72 by 73, we get 0 with a remainder of 72.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 72, we get 72.
Include the next digit (1) from the dividend after 72, then repeat: 721 / 73

Moving on to step 3:
If we divide 721 by 73, we get 9 and a remainder of 64.
Use 9 as the next digit of our solution. 
Result so far: 9.0
The remainder is 64 after subtracting 657 from 721.
Grab the next digit (6) from the dividend, add it to 64, then carry on: 646 / 73

On to step 4:
73 can be fit into 646 8 times, resulting in a remainder of 62.
Use 8 as the next digit of our solution. 
Result so far: 98.0
Subtract 584 from 646 to get 62.
Bring next digit (4) of the dividend behind the 62 and repeat the process: 624 / 73

Going ahead to step 5:
The number 73 fits into 624 8 times, leaving a remainder of 40.
Record the quotient 8 as the next digit in the result. 
Result so far: 988.0
Deduct 584 from 624 and we're left with 40.
Grab the next digit (8) from the dividend, add it to 40, then carry on: 408 / 73

Moving on to step 6:
73 can be fit into 408 5 times, resulting in a remainder of 43.
Put 5 as the next digit of the answer. 
Result so far: 9885.0
If we take 365 away from 408, we end up with 43.
Since there are no more digits in the dividend, we add a zero to the remainder making it 430, and continue the process.

Step 7:
430 divided by 73 is 5 with a remainder of 65.
The number 5 becomes the next digit in our result. 
Result so far: 9885.5
Deduct 365 from 430 and we're left with 65.
Since there are no more digits in the dividend, we add a zero to the remainder making it 650, and continue the process.

Going ahead to step 8:
If we divide 650 by 73, we get 8 and a remainder of 66.
Put 8 as the next digit of the answer. 
Result so far: 9885.58
Deduct 584 from 650 and we're left with 66.
Since there are no more digits in the dividend, we add a zero to the remainder making it 660, and continue the process.

On to step 9:
The number 73 fits into 660 9 times, leaving a remainder of 3.
The next digit of our result is 9. 
Result so far: 9885.589
The remainder is 3 after subtracting 657 from 660.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

On to step 10:
73 goes into 30 0 times with a remainder of 30.
The next digit of our result is 0. 
Result so far: 9885.589
If we subtract 0 from 30, we get 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

On to step 11:
73 can be fit into 300 4 times, resulting in a remainder of 8.
Write down 4 as next digit of the result. 
Result so far: 9885.58904
Subtract 292 from 300 to get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Advancing to step 12:
When dividing 80 by 73, we get 1 with a remainder of 7.
The number 1 becomes the next digit in our result. 
Result so far: 9885.589041
Deduct 73 from 80 and we're left with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Let's proceed to step 13:
73 goes into 70 0 times with a remainder of 70.
Put 0 as the next digit of the answer. 
Result so far: 9885.589041
If we take 0 away from 70, we end up with 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

Advancing to step 14:
73 goes into 700 9 times with a remainder of 43.
Put 9 as the next digit of the answer. 
Result so far: 9885.58904109
Subtracting 657 from 700 leaves us with 43.
Since there are no more digits in the dividend, we add a zero to the remainder making it 430, and continue the process.

Our division results in 9885.58904109 with a remaining 4.3e-08.