We look at the division of 376628 by 721 
The aim is to understand the frequency of 721 in 376628.

Step 1:
3 divided by 721 is 0 with a remainder of 3.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 3 and we're left with 3.
Grab the next digit (7) from the dividend, add it to 3, then carry on: 37 / 721

Let's proceed to step 2:
If we divide 37 by 721, we get 0 and a remainder of 37.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 37, we end up with 37.
Grab the next digit (6) from the dividend, add it to 37, then carry on: 376 / 721

Step 3:
376 divided by 721 is 0 with a remainder of 376.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we subtract 0 from 376, we get 376.
Grab the next digit (6) from the dividend, add it to 376, then carry on: 3766 / 721

Step 4:
If we divide 3766 by 721, we get 5 and a remainder of 161.
The next digit of our result is 5. 
Result so far: 5.0
If we take 3605 away from 3766, we end up with 161.
Bring next digit (2) of the dividend behind the 161 and repeat the process: 1612 / 721

Advancing to step 5:
The number 721 fits into 1612 2 times, leaving a remainder of 170.
Use 2 as the next digit of our solution. 
Result so far: 52.0
If we subtract 1442 from 1612, we get 170.
Take the next digit (8) from the dividend and append it to 170, then repeat: 1708 / 721

Let's proceed to step 6:
When dividing 1708 by 721, we get 2 with a remainder of 266.
Record the quotient 2 as the next digit in the result. 
Result so far: 522.0
If we take 1442 away from 1708, we end up with 266.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2660, and continue the process.

Going ahead to step 7:
If we divide 2660 by 721, we get 3 and a remainder of 497.
The number 3 becomes the next digit in our result. 
Result so far: 522.3
If we take 2163 away from 2660, we end up with 497.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4970, and continue the process.

On to step 8:
4970 divided by 721 is 6 with a remainder of 644.
Use 6 as the next digit of our solution. 
Result so far: 522.36
If we subtract 4326 from 4970, we get 644.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6440, and continue the process.

On to step 9:
When dividing 6440 by 721, we get 8 with a remainder of 672.
Put 8 as the next digit of the answer. 
Result so far: 522.368
Subtracting 5768 from 6440 leaves us with 672.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6720, and continue the process.

Step 10:
When dividing 6720 by 721, we get 9 with a remainder of 231.
The next digit of our result is 9. 
Result so far: 522.3689
The remainder is 231 after subtracting 6489 from 6720.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2310, and continue the process.

Let's proceed to step 11:
721 can be fit into 2310 3 times, resulting in a remainder of 147.
The number 3 becomes the next digit in our result. 
Result so far: 522.36893
Subtract 2163 from 2310 to get 147.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1470, and continue the process.

Moving on to step 12:
When dividing 1470 by 721, we get 2 with a remainder of 28.
The next digit of our result is 2. 
Result so far: 522.368932
If we take 1442 away from 1470, we end up with 28.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

Going ahead to step 13:
If we divide 280 by 721, we get 0 and a remainder of 280.
The next digit of our result is 0. 
Result so far: 522.368932
Subtracting 0 from 280 leaves us with 280.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2800, and continue the process.

On to step 14:
721 goes into 2800 3 times with a remainder of 637.
The number 3 becomes the next digit in our result. 
Result so far: 522.36893203
Deduct 2163 from 2800 and we're left with 637.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6370, and continue the process.

The final result is 522.36893203 with a remainder of 6.37e-07.