We look at the division of 643931 by 73 
The aim is to understand the frequency of 73 in 643931.

Let's proceed to step 1:
If we divide 6 by 73, we get 0 and a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 6 after subtracting 0 from 6.
Take the next digit (4) from the dividend and append it to 6, then repeat: 64 / 73

Advancing to step 2:
73 can be fit into 64 0 times, resulting in a remainder of 64.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 64 to get 64.
Include the next digit (3) from the dividend after 64, then repeat: 643 / 73

Step 3:
73 goes into 643 8 times with a remainder of 59.
Use 8 as the next digit of our solution. 
Result so far: 8.0
If we subtract 584 from 643, we get 59.
Fetch the next digit (9) from the dividend, attach it to 59 and continue: 599 / 73

Step 4:
If we divide 599 by 73, we get 8 and a remainder of 15.
Use 8 as the next digit of our solution. 
Result so far: 88.0
If we take 584 away from 599, we end up with 15.
Grab the next digit (3) from the dividend, add it to 15, then carry on: 153 / 73

Step 5:
When dividing 153 by 73, we get 2 with a remainder of 7.
The number 2 becomes the next digit in our result. 
Result so far: 882.0
Subtracting 146 from 153 leaves us with 7.
Grab the next digit (1) from the dividend, add it to 7, then carry on: 71 / 73

Step 6:
71 divided by 73 is 0 with a remainder of 71.
Use 0 as the next digit of our solution. 
Result so far: 8820.0
Subtracting 0 from 71 leaves us with 71.
Since there are no more digits in the dividend, we add a zero to the remainder making it 710, and continue the process.

On to step 7:
If we divide 710 by 73, we get 9 and a remainder of 53.
Put 9 as the next digit of the answer. 
Result so far: 8820.9
If we take 657 away from 710, we end up with 53.
Since there are no more digits in the dividend, we add a zero to the remainder making it 530, and continue the process.

Advancing to step 8:
The number 73 fits into 530 7 times, leaving a remainder of 19.
The number 7 becomes the next digit in our result. 
Result so far: 8820.97
Subtracting 511 from 530 leaves us with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

On to step 9:
73 goes into 190 2 times with a remainder of 44.
Use 2 as the next digit of our solution. 
Result so far: 8820.972
Subtracting 146 from 190 leaves us with 44.
Since there are no more digits in the dividend, we add a zero to the remainder making it 440, and continue the process.

Advancing to step 10:
When dividing 440 by 73, we get 6 with a remainder of 2.
The number 6 becomes the next digit in our result. 
Result so far: 8820.9726
Deduct 438 from 440 and we're left with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Going ahead to step 11:
73 can be fit into 20 0 times, resulting in a remainder of 20.
Put 0 as the next digit of the answer. 
Result so far: 8820.9726
If we subtract 0 from 20, we get 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Step 12:
The number 73 fits into 200 2 times, leaving a remainder of 54.
Put 2 as the next digit of the answer. 
Result so far: 8820.972602
The remainder is 54 after subtracting 146 from 200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 540, and continue the process.

Let's proceed to step 13:
When dividing 540 by 73, we get 7 with a remainder of 29.
The number 7 becomes the next digit in our result. 
Result so far: 8820.9726027
Subtracting 511 from 540 leaves us with 29.
Since there are no more digits in the dividend, we add a zero to the remainder making it 290, and continue the process.

On to step 14:
The number 73 fits into 290 3 times, leaving a remainder of 71.
Record the quotient 3 as the next digit in the result. 
Result so far: 8820.97260273
Subtract 219 from 290 to get 71.
Since there are no more digits in the dividend, we add a zero to the remainder making it 710, and continue the process.

After the division, we end up with 8820.97260273 and a remainder of 7.1e-08.