We look at the division of 42078904 by 721 
The aim is to understand the frequency of 721 in 42078904.

On to step 1:
If we divide 4 by 721, we get 0 and a remainder of 4.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 4 to get 4.
Include the next digit (2) from the dividend after 4, then repeat: 42 / 721

Moving on to step 2:
If we divide 42 by 721, we get 0 and a remainder of 42.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 42, we get 42.
Include the next digit (0) from the dividend after 42, then repeat: 420 / 721

Step 3:
The number 721 fits into 420 0 times, leaving a remainder of 420.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 420, we end up with 420.
Bring next digit (7) of the dividend behind the 420 and repeat the process: 4207 / 721

On to step 4:
4207 divided by 721 is 5 with a remainder of 602.
Write down 5 as next digit of the result. 
Result so far: 5.0
Subtract 3605 from 4207 to get 602.
Bring next digit (8) of the dividend behind the 602 and repeat the process: 6028 / 721

Going ahead to step 5:
The number 721 fits into 6028 8 times, leaving a remainder of 260.
Record the quotient 8 as the next digit in the result. 
Result so far: 58.0
Deduct 5768 from 6028 and we're left with 260.
Append the next digit (9) from the dividend to 260 and continue with: 2609 / 721

Advancing to step 6:
If we divide 2609 by 721, we get 3 and a remainder of 446.
Record the quotient 3 as the next digit in the result. 
Result so far: 583.0
The remainder is 446 after subtracting 2163 from 2609.
Append the next digit (0) from the dividend to 446 and continue with: 4460 / 721

Moving on to step 7:
When dividing 4460 by 721, we get 6 with a remainder of 134.
The number 6 becomes the next digit in our result. 
Result so far: 5836.0
If we subtract 4326 from 4460, we get 134.
Fetch the next digit (4) from the dividend, attach it to 134 and continue: 1344 / 721

On to step 8:
721 can be fit into 1344 1 times, resulting in a remainder of 623.
Write down 1 as next digit of the result. 
Result so far: 58361.0
The remainder is 623 after subtracting 721 from 1344.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6230, and continue the process.

Let's proceed to step 9:
721 can be fit into 6230 8 times, resulting in a remainder of 462.
Write down 8 as next digit of the result. 
Result so far: 58361.8
The remainder is 462 after subtracting 5768 from 6230.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4620, and continue the process.

Step 10:
If we divide 4620 by 721, we get 6 and a remainder of 294.
Use 6 as the next digit of our solution. 
Result so far: 58361.86
Deduct 4326 from 4620 and we're left with 294.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2940, and continue the process.

Moving on to step 11:
When dividing 2940 by 721, we get 4 with a remainder of 56.
Put 4 as the next digit of the answer. 
Result so far: 58361.864
If we subtract 2884 from 2940, we get 56.
Since there are no more digits in the dividend, we add a zero to the remainder making it 560, and continue the process.

Going ahead to step 12:
When dividing 560 by 721, we get 0 with a remainder of 560.
Record the quotient 0 as the next digit in the result. 
Result so far: 58361.864
Subtract 0 from 560 to get 560.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5600, and continue the process.

Let's proceed to step 13:
When dividing 5600 by 721, we get 7 with a remainder of 553.
Use 7 as the next digit of our solution. 
Result so far: 58361.86407
The remainder is 553 after subtracting 5047 from 5600.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5530, and continue the process.

Step 14:
5530 divided by 721 is 7 with a remainder of 483.
Record the quotient 7 as the next digit in the result. 
Result so far: 58361.864077
Subtracting 5047 from 5530 leaves us with 483.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4830, and continue the process.

The final result is 58361.864077 with a remainder of 4.83e-05.