We're dividing 138519 by 12 
We want to figure out the number of times 138519 can be divided by 12.

Step 1:
When dividing 1 by 12, we get 0 with a remainder of 1.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 1 to get 1.
Include the next digit (3) from the dividend after 1, then repeat: 13 / 12

Advancing to step 2:
12 goes into 13 1 times with a remainder of 1.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
If we subtract 12 from 13, we get 1.
Fetch the next digit (8) from the dividend, attach it to 1 and continue: 18 / 12

Going ahead to step 3:
If we divide 18 by 12, we get 1 and a remainder of 6.
Record the quotient 1 as the next digit in the result. 
Result so far: 11.0
The remainder is 6 after subtracting 12 from 18.
Include the next digit (5) from the dividend after 6, then repeat: 65 / 12

On to step 4:
The number 12 fits into 65 5 times, leaving a remainder of 5.
Write down 5 as next digit of the result. 
Result so far: 115.0
The remainder is 5 after subtracting 60 from 65.
Bring next digit (1) of the dividend behind the 5 and repeat the process: 51 / 12

On to step 5:
12 can be fit into 51 4 times, resulting in a remainder of 3.
Write down 4 as next digit of the result. 
Result so far: 1154.0
Subtracting 48 from 51 leaves us with 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 12

Going ahead to step 6:
When dividing 39 by 12, we get 3 with a remainder of 3.
Use 3 as the next digit of our solution. 
Result so far: 11543.0
Deduct 36 from 39 and we're left with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Let's proceed to step 7:
30 divided by 12 is 2 with a remainder of 6.
Put 2 as the next digit of the answer. 
Result so far: 11543.2
Subtract 24 from 30 to get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

On to step 8:
If we divide 60 by 12, we get 5 and a remainder of 0.
Write down 5 as next digit of the result. 
Result so far: 11543.25
Deduct 60 from 60 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Let's proceed to step 9:
12 can be fit into 0 0 times, resulting in a remainder of 0.
The next digit of our result is 0. 
Result so far: 11543.25
Deduct 0 from 0 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Moving on to step 10:
When dividing 0 by 12, we get 0 with a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 11543.25
Subtracting 0 from 0 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The quotient of the division is 11543.25, and the remainder is 0.0.