We're dividing 149355 by 12 
Let's see how many times 12 fits into 149355.

Step 1:
If we divide 1 by 12, we get 0 and a remainder of 1.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 1 leaves us with 1.
Append the next digit (4) from the dividend to 1 and continue with: 14 / 12

Let's proceed to step 2:
The number 12 fits into 14 1 times, leaving a remainder of 2.
Put 1 as the next digit of the answer. 
Result so far: 1.0
If we subtract 12 from 14, we get 2.
Grab the next digit (9) from the dividend, add it to 2, then carry on: 29 / 12

Going ahead to step 3:
29 divided by 12 is 2 with a remainder of 5.
Write down 2 as next digit of the result. 
Result so far: 12.0
The remainder is 5 after subtracting 24 from 29.
Grab the next digit (3) from the dividend, add it to 5, then carry on: 53 / 12

On to step 4:
If we divide 53 by 12, we get 4 and a remainder of 5.
Record the quotient 4 as the next digit in the result. 
Result so far: 124.0
If we subtract 48 from 53, we get 5.
Fetch the next digit (5) from the dividend, attach it to 5 and continue: 55 / 12

Step 5:
The number 12 fits into 55 4 times, leaving a remainder of 7.
The next digit of our result is 4. 
Result so far: 1244.0
The remainder is 7 after subtracting 48 from 55.
Bring next digit (5) of the dividend behind the 7 and repeat the process: 75 / 12

Step 6:
The number 12 fits into 75 6 times, leaving a remainder of 3.
Record the quotient 6 as the next digit in the result. 
Result so far: 12446.0
Deduct 72 from 75 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.

On to step 7:
30 divided by 12 is 2 with a remainder of 6.
Record the quotient 2 as the next digit in the result. 
Result so far: 12446.2
The remainder is 6 after subtracting 24 from 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Let's proceed to step 8:
12 goes into 60 5 times with a remainder of 0.
The number 5 becomes the next digit in our result. 
Result so far: 12446.25
Subtract 60 from 60 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing to step 9:
The number 12 fits into 0 0 times, leaving a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 12446.25
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.

Advancing to step 10:
If we divide 0 by 12, we get 0 and a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 12446.25
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.

The final outcome is 12446.25, with a leftover of 0.0.