We're dividing 172840 by 12 
We're looking to find how many times 12 goes into 172840.

Step 1:
When dividing 1 by 12, we get 0 with a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 1 to get 1.
Fetch the next digit (7) from the dividend, attach it to 1 and continue: 17 / 12

Going ahead to step 2:
The number 12 fits into 17 1 times, leaving a remainder of 5.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Deduct 12 from 17 and we're left with 5.
Fetch the next digit (2) from the dividend, attach it to 5 and continue: 52 / 12

Step 3:
12 goes into 52 4 times with a remainder of 4.
Use 4 as the next digit of our solution. 
Result so far: 14.0
If we take 48 away from 52, we end up with 4.
Fetch the next digit (8) from the dividend, attach it to 4 and continue: 48 / 12

Moving on to step 4:
12 can be fit into 48 4 times, resulting in a remainder of 0.
Record the quotient 4 as the next digit in the result. 
Result so far: 144.0
Deduct 48 from 48 and we're left with 0.
Fetch the next digit (4) from the dividend, attach it to 0 and continue: 4 / 12

Going ahead to step 5:
12 goes into 4 0 times with a remainder of 4.
Use 0 as the next digit of our solution. 
Result so far: 1440.0
If we subtract 0 from 4, we get 4.
Bring next digit (0) of the dividend behind the 4 and repeat the process: 40 / 12

Going ahead to step 6:
When dividing 40 by 12, we get 3 with a remainder of 4.
Put 3 as the next digit of the answer. 
Result so far: 14403.0
Deduct 36 from 40 and we're left with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Going ahead to step 7:
If we divide 40 by 12, we get 3 and a remainder of 4.
The next digit of our result is 3. 
Result so far: 14403.3
If we subtract 36 from 40, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

On to step 8:
12 can be fit into 40 3 times, resulting in a remainder of 4.
Use 3 as the next digit of our solution. 
Result so far: 14403.33
Subtract 36 from 40 to get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

The quotient of the division is 14403.33, and the remainder is 0.004.