Let's divide 12109 by 10
Let's see how many times 10 fits into 12109.

Going ahead to step 1:
10 can be fit into 1 0 times, resulting in a remainder of 1.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 1, we get 1.
Take the next digit (2) from the dividend and append it to 1, then repeat: 12 / 10

Step 2:
12 divided by 10 is 1 with a remainder of 2.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
Subtract 10 from 12 to get 2.
Take the next digit (1) from the dividend and append it to 2, then repeat: 21 / 10

Step 3:
21 divided by 10 is 2 with a remainder of 1.
Put 2 as the next digit of the answer. 
Result so far: 12.0
Subtract 20 from 21 to get 1.
Bring next digit (0) of the dividend behind the 1 and repeat the process: 10 / 10

On to step 4:
10 goes into 10 1 times with a remainder of 0.
The next digit of our result is 1. 
Result so far: 121.0
If we take 10 away from 10, we end up with 0.
Fetch the next digit (9) from the dividend, attach it to 0 and continue: 9 / 10

On to step 5:
10 goes into 9 0 times with a remainder of 9.
Use 0 as the next digit of our solution. 
Result so far: 1210.0
Subtracting 0 from 9 leaves us with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Let's proceed to step 6:
If we divide 90 by 10, we get 9 and a remainder of 0.
Write down 9 as next digit of the result. 
Result so far: 1210.9
Deduct 90 from 90 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 7:
0 divided by 10 is 0 with a remainder of 0.
The next digit of our result is 0. 
Result so far: 1210.9
If we take 0 away from 0, we end up 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.

Going ahead to step 8:
10 goes into 0 0 times with a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 1210.9
The remainder is 0 after subtracting 0 from 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Our division results in 1210.9 with a remaining 0.0.