We're dividing 131209 by 10 
Let's see how many times 10 fits into 131209.

Let's proceed to step 1:
1 divided by 10 is 0 with a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 1, we end up with 1.
Bring next digit (3) of the dividend behind the 1 and repeat the process: 13 / 10

On to step 2:
10 goes into 13 1 times with a remainder of 3.
Write down 1 as next digit of the result. 
Result so far: 1.0
If we take 10 away from 13, we end up with 3.
Bring next digit (1) of the dividend behind the 3 and repeat the process: 31 / 10

Going ahead to step 3:
When dividing 31 by 10, we get 3 with a remainder of 1.
Write down 3 as next digit of the result. 
Result so far: 13.0
Subtracting 30 from 31 leaves us with 1.
Take the next digit (2) from the dividend and append it to 1, then repeat: 12 / 10

Step 4:
10 can be fit into 12 1 times, resulting in a remainder of 2.
Record the quotient 1 as the next digit in the result. 
Result so far: 131.0
Subtract 10 from 12 to get 2.
Take the next digit (0) from the dividend and append it to 2, then repeat: 20 / 10

Going ahead to step 5:
10 goes into 20 2 times with a remainder of 0.
Record the quotient 2 as the next digit in the result. 
Result so far: 1312.0
Subtract 20 from 20 to get 0.
Take the next digit (9) from the dividend and append it to 0, then repeat: 9 / 10

Advancing to step 6:
10 can be fit into 9 0 times, resulting in a remainder of 9.
The next digit of our result is 0. 
Result so far: 13120.0
If we take 0 away from 9, we end up 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.

On to step 7:
10 can be fit into 90 9 times, resulting in a remainder of 0.
The number 9 becomes the next digit in our result. 
Result so far: 13120.9
If we take 90 away from 90, 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.

Moving on to step 8:
0 divided by 10 is 0 with a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 13120.9
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.

Advancing to step 9:
When dividing 0 by 10, we get 0 with a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 13120.9
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.

The final result is 13120.9 with a remainder of 0.0.