We look at the division of 155509 by 3 
The aim is to understand the frequency of 3 in 155509.

Step 1:
When dividing 1 by 3, we get 0 with a remainder of 1.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 1, we end up with 1.
Take the next digit (5) from the dividend and append it to 1, then repeat: 15 / 3

On to step 2:
The number 3 fits into 15 5 times, leaving a remainder of 0.
Put 5 as the next digit of the answer. 
Result so far: 5.0
Subtracting 15 from 15 leaves us with 0.
Grab the next digit (5) from the dividend, add it to 0, then carry on: 5 / 3

Moving on to step 3:
The number 3 fits into 5 1 times, leaving a remainder of 2.
Record the quotient 1 as the next digit in the result. 
Result so far: 51.0
Deduct 3 from 5 and we're left with 2.
Bring next digit (5) of the dividend behind the 2 and repeat the process: 25 / 3

On to step 4:
3 can be fit into 25 8 times, resulting in a remainder of 1.
Use 8 as the next digit of our solution. 
Result so far: 518.0
Subtract 24 from 25 to get 1.
Bring next digit (0) of the dividend behind the 1 and repeat the process: 10 / 3

Going ahead to step 5:
10 divided by 3 is 3 with a remainder of 1.
Write down 3 as next digit of the result. 
Result so far: 5183.0
The remainder is 1 after subtracting 9 from 10.
Fetch the next digit (9) from the dividend, attach it to 1 and continue: 19 / 3

Moving on to step 6:
When dividing 19 by 3, we get 6 with a remainder of 1.
Put 6 as the next digit of the answer. 
Result so far: 51836.0
If we take 18 away from 19, we end up with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

On to step 7:
If we divide 10 by 3, we get 3 and a remainder of 1.
Write down 3 as next digit of the result. 
Result so far: 51836.3
Subtract 9 from 10 to get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

On to step 8:
10 divided by 3 is 3 with a remainder of 1.
Use 3 as the next digit of our solution. 
Result so far: 51836.33
Subtracting 9 from 10 leaves us with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

The final outcome is 51836.33, with a leftover of 0.001.