We look at the division of 81040409 by 507 
The aim is to understand the frequency of 507 in 81040409.

Advancing to step 1:
507 can be fit into 8 0 times, resulting in a remainder of 8.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 8 leaves us with 8.
Take the next digit (1) from the dividend and append it to 8, then repeat: 81 / 507

Moving on to step 2:
When dividing 81 by 507, we get 0 with a remainder of 81.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 81, we end up with 81.
Bring next digit (0) of the dividend behind the 81 and repeat the process: 810 / 507

Advancing to step 3:
The number 507 fits into 810 1 times, leaving a remainder of 303.
The next digit of our result is 1. 
Result so far: 1.0
Subtracting 507 from 810 leaves us with 303.
Append the next digit (4) from the dividend to 303 and continue with: 3034 / 507

Advancing to step 4:
507 can be fit into 3034 5 times, resulting in a remainder of 499.
Put 5 as the next digit of the answer. 
Result so far: 15.0
The remainder is 499 after subtracting 2535 from 3034.
Include the next digit (0) from the dividend after 499, then repeat: 4990 / 507

Moving on to step 5:
4990 divided by 507 is 9 with a remainder of 427.
The number 9 becomes the next digit in our result. 
Result so far: 159.0
If we subtract 4563 from 4990, we get 427.
Grab the next digit (4) from the dividend, add it to 427, then carry on: 4274 / 507

Step 6:
If we divide 4274 by 507, we get 8 and a remainder of 218.
The next digit of our result is 8. 
Result so far: 1598.0
If we subtract 4056 from 4274, we get 218.
Grab the next digit (0) from the dividend, add it to 218, then carry on: 2180 / 507

Moving on to step 7:
2180 divided by 507 is 4 with a remainder of 152.
Put 4 as the next digit of the answer. 
Result so far: 15984.0
Subtract 2028 from 2180 to get 152.
Include the next digit (9) from the dividend after 152, then repeat: 1529 / 507

Let's proceed to step 8:
If we divide 1529 by 507, we get 3 and a remainder of 8.
Record the quotient 3 as the next digit in the result. 
Result so far: 159843.0
If we take 1521 away from 1529, we end up with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Advancing to step 9:
If we divide 80 by 507, we get 0 and a remainder of 80.
Write down 0 as next digit of the result. 
Result so far: 159843.0
Subtracting 0 from 80 leaves us with 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

Let's proceed to step 10:
When dividing 800 by 507, we get 1 with a remainder of 293.
Write down 1 as next digit of the result. 
Result so far: 159843.01
Deduct 507 from 800 and we're left with 293.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2930, and continue the process.

Moving on to step 11:
507 can be fit into 2930 5 times, resulting in a remainder of 395.
Put 5 as the next digit of the answer. 
Result so far: 159843.015
Subtracting 2535 from 2930 leaves us with 395.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3950, and continue the process.

Moving on to step 12:
3950 divided by 507 is 7 with a remainder of 401.
Record the quotient 7 as the next digit in the result. 
Result so far: 159843.0157
If we take 3549 away from 3950, we end up with 401.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4010, and continue the process.

On to step 13:
4010 divided by 507 is 7 with a remainder of 461.
Put 7 as the next digit of the answer. 
Result so far: 159843.01577
If we take 3549 away from 4010, we end up with 461.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4610, and continue the process.

The final outcome is 159843.01577, with a leftover of 0.000461.