72404934 ÷ 321 
The aim is to understand the frequency of 321 in 72404934.

Step 1:
321 goes into 7 0 times with a remainder of 7.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 7 leaves us with 7.
Fetch the next digit (2) from the dividend, attach it to 7 and continue: 72 / 321

Moving on to step 2:
321 goes into 72 0 times with a remainder of 72.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 72 after subtracting 0 from 72.
Include the next digit (4) from the dividend after 72, then repeat: 724 / 321

On to step 3:
If we divide 724 by 321, we get 2 and a remainder of 82.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
If we take 642 away from 724, we end up with 82.
Include the next digit (0) from the dividend after 82, then repeat: 820 / 321

Advancing to step 4:
820 divided by 321 is 2 with a remainder of 178.
Use 2 as the next digit of our solution. 
Result so far: 22.0
If we take 642 away from 820, we end up with 178.
Append the next digit (4) from the dividend to 178 and continue with: 1784 / 321

Going ahead to step 5:
The number 321 fits into 1784 5 times, leaving a remainder of 179.
Write down 5 as next digit of the result. 
Result so far: 225.0
If we subtract 1605 from 1784, we get 179.
Take the next digit (9) from the dividend and append it to 179, then repeat: 1799 / 321

Advancing to step 6:
1799 divided by 321 is 5 with a remainder of 194.
Put 5 as the next digit of the answer. 
Result so far: 2255.0
Deduct 1605 from 1799 and we're left with 194.
Bring next digit (3) of the dividend behind the 194 and repeat the process: 1943 / 321

Going ahead to step 7:
If we divide 1943 by 321, we get 6 and a remainder of 17.
The number 6 becomes the next digit in our result. 
Result so far: 22556.0
If we take 1926 away from 1943, we end up with 17.
Bring next digit (4) of the dividend behind the 17 and repeat the process: 174 / 321

Going ahead to step 8:
321 goes into 174 0 times with a remainder of 174.
The number 0 becomes the next digit in our result. 
Result so far: 225560.0
Subtracting 0 from 174 leaves us with 174.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1740, and continue the process.

On to step 9:
When dividing 1740 by 321, we get 5 with a remainder of 135.
Record the quotient 5 as the next digit in the result. 
Result so far: 225560.5
If we subtract 1605 from 1740, we get 135.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1350, and continue the process.

On to step 10:
The number 321 fits into 1350 4 times, leaving a remainder of 66.
The number 4 becomes the next digit in our result. 
Result so far: 225560.54
The remainder is 66 after subtracting 1284 from 1350.
Since there are no more digits in the dividend, we add a zero to the remainder making it 660, and continue the process.

Going ahead to step 11:
The number 321 fits into 660 2 times, leaving a remainder of 18.
Record the quotient 2 as the next digit in the result. 
Result so far: 225560.542
Subtracting 642 from 660 leaves us with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Advancing to step 12:
The number 321 fits into 180 0 times, leaving a remainder of 180.
Use 0 as the next digit of our solution. 
Result so far: 225560.542
Deduct 0 from 180 and we're left with 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1800, and continue the process.

Advancing to step 13:
The number 321 fits into 1800 5 times, leaving a remainder of 195.
The next digit of our result is 5. 
Result so far: 225560.54205
The remainder is 195 after subtracting 1605 from 1800.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1950, and continue the process.

Going ahead to step 14:
When dividing 1950 by 321, we get 6 with a remainder of 24.
The number 6 becomes the next digit in our result. 
Result so far: 225560.542056
Subtracting 1926 from 1950 leaves us with 24.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

Moving on to step 15:
321 can be fit into 240 0 times, resulting in a remainder of 240.
Use 0 as the next digit of our solution. 
Result so far: 225560.542056
If we subtract 0 from 240, we get 240.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2400, and continue the process.

Going ahead to step 16:
When dividing 2400 by 321, we get 7 with a remainder of 153.
Use 7 as the next digit of our solution. 
Result so far: 225560.54205607
Subtract 2247 from 2400 to get 153.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1530, and continue the process.

The final result is 225560.54205607 with a remainder of 1.53e-07.