Let's divide 137878 by 3
The aim is to understand the frequency of 3 in 137878.

Let's proceed to step 1:
3 can be fit into 1 0 times, resulting in a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 1, we end up with 1.
Include the next digit (3) from the dividend after 1, then repeat: 13 / 3

Moving on to step 2:
The number 3 fits into 13 4 times, leaving a remainder of 1.
Use 4 as the next digit of our solution. 
Result so far: 4.0
If we take 12 away from 13, we end up with 1.
Fetch the next digit (7) from the dividend, attach it to 1 and continue: 17 / 3

Step 3:
3 goes into 17 5 times with a remainder of 2.
Use 5 as the next digit of our solution. 
Result so far: 45.0
Subtracting 15 from 17 leaves us with 2.
Bring next digit (8) of the dividend behind the 2 and repeat the process: 28 / 3

Step 4:
3 goes into 28 9 times with a remainder of 1.
The next digit of our result is 9. 
Result so far: 459.0
Subtract 27 from 28 to get 1.
Bring next digit (7) of the dividend behind the 1 and repeat the process: 17 / 3

On to step 5:
When dividing 17 by 3, we get 5 with a remainder of 2.
The next digit of our result is 5. 
Result so far: 4595.0
The remainder is 2 after subtracting 15 from 17.
Fetch the next digit (8) from the dividend, attach it to 2 and continue: 28 / 3

Let's proceed to step 6:
28 divided by 3 is 9 with a remainder of 1.
Put 9 as the next digit of the answer. 
Result so far: 45959.0
If we subtract 27 from 28, we 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.

Advancing to step 7:
The number 3 fits into 10 3 times, leaving a remainder of 1.
Use 3 as the next digit of our solution. 
Result so far: 45959.3
The remainder is 1 after subtracting 9 from 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Going ahead to step 8:
10 divided by 3 is 3 with a remainder of 1.
The next digit of our result is 3. 
Result so far: 45959.33
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.

After the division, we end up with 45959.33 and a remainder of 0.001.