We look at the division of 421720 by 73 
The aim is to understand the frequency of 73 in 421720.

Step 1:
The number 73 fits into 4 0 times, leaving a remainder of 4.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 4, we end up with 4.
Include the next digit (2) from the dividend after 4, then repeat: 42 / 73

Advancing to step 2:
When dividing 42 by 73, we get 0 with a remainder of 42.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 42 after subtracting 0 from 42.
Include the next digit (1) from the dividend after 42, then repeat: 421 / 73

Going ahead to step 3:
If we divide 421 by 73, we get 5 and a remainder of 56.
The next digit of our result is 5. 
Result so far: 5.0
The remainder is 56 after subtracting 365 from 421.
Include the next digit (7) from the dividend after 56, then repeat: 567 / 73

Let's proceed to step 4:
567 divided by 73 is 7 with a remainder of 56.
The number 7 becomes the next digit in our result. 
Result so far: 57.0
If we subtract 511 from 567, we get 56.
Bring next digit (2) of the dividend behind the 56 and repeat the process: 562 / 73

Let's proceed to step 5:
562 divided by 73 is 7 with a remainder of 51.
Put 7 as the next digit of the answer. 
Result so far: 577.0
Deduct 511 from 562 and we're left with 51.
Fetch the next digit (0) from the dividend, attach it to 51 and continue: 510 / 73

On to step 6:
73 goes into 510 6 times with a remainder of 72.
The next digit of our result is 6. 
Result so far: 5776.0
Subtracting 438 from 510 leaves us with 72.
Since there are no more digits in the dividend, we add a zero to the remainder making it 720, and continue the process.

Going ahead to step 7:
720 divided by 73 is 9 with a remainder of 63.
The number 9 becomes the next digit in our result. 
Result so far: 5776.9
Deduct 657 from 720 and we're left with 63.
Since there are no more digits in the dividend, we add a zero to the remainder making it 630, and continue the process.

On to step 8:
If we divide 630 by 73, we get 8 and a remainder of 46.
The number 8 becomes the next digit in our result. 
Result so far: 5776.98
Deduct 584 from 630 and we're left with 46.
Since there are no more digits in the dividend, we add a zero to the remainder making it 460, and continue the process.

On to step 9:
If we divide 460 by 73, we get 6 and a remainder of 22.
Write down 6 as next digit of the result. 
Result so far: 5776.986
Deduct 438 from 460 and we're left with 22.
Since there are no more digits in the dividend, we add a zero to the remainder making it 220, and continue the process.

On to step 10:
73 goes into 220 3 times with a remainder of 1.
The next digit of our result is 3. 
Result so far: 5776.9863
Subtracting 219 from 220 leaves us with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

On to step 11:
If we divide 10 by 73, we get 0 and a remainder of 10.
The next digit of our result is 0. 
Result so far: 5776.9863
Subtracting 0 from 10 leaves us with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Going ahead to step 12:
73 goes into 100 1 times with a remainder of 27.
Put 1 as the next digit of the answer. 
Result so far: 5776.986301
Subtract 73 from 100 to get 27.
Since there are no more digits in the dividend, we add a zero to the remainder making it 270, and continue the process.

Advancing to step 13:
73 can be fit into 270 3 times, resulting in a remainder of 51.
Use 3 as the next digit of our solution. 
Result so far: 5776.9863013
The remainder is 51 after subtracting 219 from 270.
Since there are no more digits in the dividend, we add a zero to the remainder making it 510, and continue the process.

Step 14:
If we divide 510 by 73, we get 6 and a remainder of 72.
The number 6 becomes the next digit in our result. 
Result so far: 5776.98630136
Deduct 438 from 510 and we're left with 72.
Since there are no more digits in the dividend, we add a zero to the remainder making it 720, and continue the process.

The quotient of the division is 5776.98630136, and the remainder is 7.2e-08.