Let's divide 72873103 by 521
The aim is to understand the frequency of 521 in 72873103.

On to step 1:
When dividing 7 by 521, we get 0 with a remainder of 7.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 7, we end up with 7.
Include the next digit (2) from the dividend after 7, then repeat: 72 / 521

Going ahead to step 2:
When dividing 72 by 521, we get 0 with a remainder of 72.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 72 and we're left with 72.
Include the next digit (8) from the dividend after 72, then repeat: 728 / 521

Let's proceed to step 3:
521 goes into 728 1 times with a remainder of 207.
The next digit of our result is 1. 
Result so far: 1.0
Deduct 521 from 728 and we're left with 207.
Grab the next digit (7) from the dividend, add it to 207, then carry on: 2077 / 521

Let's proceed to step 4:
If we divide 2077 by 521, we get 3 and a remainder of 514.
The number 3 becomes the next digit in our result. 
Result so far: 13.0
Subtract 1563 from 2077 to get 514.
Include the next digit (3) from the dividend after 514, then repeat: 5143 / 521

Step 5:
5143 divided by 521 is 9 with a remainder of 454.
Record the quotient 9 as the next digit in the result. 
Result so far: 139.0
If we subtract 4689 from 5143, we get 454.
Bring next digit (1) of the dividend behind the 454 and repeat the process: 4541 / 521

Moving on to step 6:
4541 divided by 521 is 8 with a remainder of 373.
Write down 8 as next digit of the result. 
Result so far: 1398.0
Subtracting 4168 from 4541 leaves us with 373.
Fetch the next digit (0) from the dividend, attach it to 373 and continue: 3730 / 521

Step 7:
521 goes into 3730 7 times with a remainder of 83.
Write down 7 as next digit of the result. 
Result so far: 13987.0
Deduct 3647 from 3730 and we're left with 83.
Append the next digit (3) from the dividend to 83 and continue with: 833 / 521

Step 8:
The number 521 fits into 833 1 times, leaving a remainder of 312.
Record the quotient 1 as the next digit in the result. 
Result so far: 139871.0
Deduct 521 from 833 and we're left with 312.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3120, and continue the process.

Let's proceed to step 9:
521 can be fit into 3120 5 times, resulting in a remainder of 515.
Record the quotient 5 as the next digit in the result. 
Result so far: 139871.5
If we take 2605 away from 3120, we end up with 515.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5150, and continue the process.

Advancing to step 10:
The number 521 fits into 5150 9 times, leaving a remainder of 461.
The next digit of our result is 9. 
Result so far: 139871.59
If we subtract 4689 from 5150, we get 461.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4610, and continue the process.

Let's proceed to step 11:
If we divide 4610 by 521, we get 8 and a remainder of 442.
Record the quotient 8 as the next digit in the result. 
Result so far: 139871.598
If we take 4168 away from 4610, we end up with 442.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4420, and continue the process.

Moving on to step 12:
The number 521 fits into 4420 8 times, leaving a remainder of 252.
Write down 8 as next digit of the result. 
Result so far: 139871.5988
The remainder is 252 after subtracting 4168 from 4420.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2520, and continue the process.

Our division results in 139871.5988 with a remaining 0.00252.