We look at the division of 53993848 by 509 
The aim is to understand the frequency of 509 in 53993848.

On to step 1:
509 can be fit into 5 0 times, resulting in a remainder of 5.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Fetch the next digit (3) from the dividend, attach it to 5 and continue: 53 / 509

On to step 2:
509 goes into 53 0 times with a remainder of 53.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 53, we end up with 53.
Bring next digit (9) of the dividend behind the 53 and repeat the process: 539 / 509

Step 3:
509 goes into 539 1 times with a remainder of 30.
Put 1 as the next digit of the answer. 
Result so far: 1.0
The remainder is 30 after subtracting 509 from 539.
Bring next digit (9) of the dividend behind the 30 and repeat the process: 309 / 509

On to step 4:
If we divide 309 by 509, we get 0 and a remainder of 309.
Write down 0 as next digit of the result. 
Result so far: 10.0
If we take 0 away from 309, we end up with 309.
Append the next digit (3) from the dividend to 309 and continue with: 3093 / 509

Advancing to step 5:
If we divide 3093 by 509, we get 6 and a remainder of 39.
Use 6 as the next digit of our solution. 
Result so far: 106.0
Deduct 3054 from 3093 and we're left with 39.
Grab the next digit (8) from the dividend, add it to 39, then carry on: 398 / 509

Step 6:
398 divided by 509 is 0 with a remainder of 398.
Write down 0 as next digit of the result. 
Result so far: 1060.0
Subtract 0 from 398 to get 398.
Fetch the next digit (4) from the dividend, attach it to 398 and continue: 3984 / 509

Going ahead to step 7:
The number 509 fits into 3984 7 times, leaving a remainder of 421.
The number 7 becomes the next digit in our result. 
Result so far: 10607.0
The remainder is 421 after subtracting 3563 from 3984.
Append the next digit (8) from the dividend to 421 and continue with: 4218 / 509

Going ahead to step 8:
When dividing 4218 by 509, we get 8 with a remainder of 146.
The number 8 becomes the next digit in our result. 
Result so far: 106078.0
Subtract 4072 from 4218 to get 146.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1460, and continue the process.

Advancing to step 9:
When dividing 1460 by 509, we get 2 with a remainder of 442.
Write down 2 as next digit of the result. 
Result so far: 106078.2
If we subtract 1018 from 1460, we get 442.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4420, and continue the process.

Going ahead to step 10:
4420 divided by 509 is 8 with a remainder of 348.
Write down 8 as next digit of the result. 
Result so far: 106078.28
If we take 4072 away from 4420, we end up with 348.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3480, and continue the process.

Let's proceed to step 11:
3480 divided by 509 is 6 with a remainder of 426.
Record the quotient 6 as the next digit in the result. 
Result so far: 106078.286
If we subtract 3054 from 3480, we get 426.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4260, and continue the process.

On to step 12:
509 goes into 4260 8 times with a remainder of 188.
Use 8 as the next digit of our solution. 
Result so far: 106078.2868
If we subtract 4072 from 4260, we get 188.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1880, and continue the process.

On to step 13:
When dividing 1880 by 509, we get 3 with a remainder of 353.
The number 3 becomes the next digit in our result. 
Result so far: 106078.28683
Subtracting 1527 from 1880 leaves us with 353.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3530, and continue the process.

Step 14:
509 goes into 3530 6 times with a remainder of 476.
Use 6 as the next digit of our solution. 
Result so far: 106078.286836
Subtracting 3054 from 3530 leaves us with 476.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4760, and continue the process.

Advancing to step 15:
The number 509 fits into 4760 9 times, leaving a remainder of 179.
Put 9 as the next digit of the answer. 
Result so far: 106078.2868369
If we subtract 4581 from 4760, we get 179.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1790, and continue the process.

Step 16:
509 can be fit into 1790 3 times, resulting in a remainder of 263.
Put 3 as the next digit of the answer. 
Result so far: 106078.28683693
If we take 1527 away from 1790, we end up with 263.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2630, and continue the process.

The final result is 106078.28683693 with a remainder of 2.63e-07.