129912 ÷ 18 
We're looking to find how many times 18 goes into 129912.

Moving on to step 1:
If we divide 1 by 18, we get 0 and a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 1 and we're left with 1.
Grab the next digit (2) from the dividend, add it to 1, then carry on: 12 / 18

Advancing to step 2:
The number 18 fits into 12 0 times, leaving a remainder of 12.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Deduct 0 from 12 and we're left with 12.
Grab the next digit (9) from the dividend, add it to 12, then carry on: 129 / 18

Moving on to step 3:
The number 18 fits into 129 7 times, leaving a remainder of 3.
Write down 7 as next digit of the result. 
Result so far: 7.0
If we subtract 126 from 129, we get 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 18

On to step 4:
39 divided by 18 is 2 with a remainder of 3.
Put 2 as the next digit of the answer. 
Result so far: 72.0
Deduct 36 from 39 and we're left with 3.
Take the next digit (1) from the dividend and append it to 3, then repeat: 31 / 18

Going ahead to step 5:
When dividing 31 by 18, we get 1 with a remainder of 13.
Record the quotient 1 as the next digit in the result. 
Result so far: 721.0
Deduct 18 from 31 and we're left with 13.
Append the next digit (2) from the dividend to 13 and continue with: 132 / 18

Moving on to step 6:
If we divide 132 by 18, we get 7 and a remainder of 6.
Use 7 as the next digit of our solution. 
Result so far: 7217.0
Subtracting 126 from 132 leaves us with 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 7:
18 can be fit into 60 3 times, resulting in a remainder of 6.
The number 3 becomes the next digit in our result. 
Result so far: 7217.3
Subtract 54 from 60 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.

Advancing to step 8:
If we divide 60 by 18, we get 3 and a remainder of 6.
Write down 3 as next digit of the result. 
Result so far: 7217.33
If we take 54 away from 60, we end up with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

The final result is 7217.33 with a remainder of 0.006.