We're dividing 125866 by 15 
We're looking to find how many times 15 goes into 125866.

Advancing to step 1:
15 can be fit into 1 0 times, resulting in a remainder of 1.
Use 0 as the next digit of our solution. 
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 / 15

Step 2:
12 divided by 15 is 0 with a remainder of 12.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 12 after subtracting 0 from 12.
Include the next digit (5) from the dividend after 12, then repeat: 125 / 15

Going ahead to step 3:
15 can be fit into 125 8 times, resulting in a remainder of 5.
The number 8 becomes the next digit in our result. 
Result so far: 8.0
If we take 120 away from 125, we end up with 5.
Take the next digit (8) from the dividend and append it to 5, then repeat: 58 / 15

Going ahead to step 4:
58 divided by 15 is 3 with a remainder of 13.
Put 3 as the next digit of the answer. 
Result so far: 83.0
Deduct 45 from 58 and we're left with 13.
Append the next digit (6) from the dividend to 13 and continue with: 136 / 15

Step 5:
When dividing 136 by 15, we get 9 with a remainder of 1.
Put 9 as the next digit of the answer. 
Result so far: 839.0
Subtracting 135 from 136 leaves us with 1.
Include the next digit (6) from the dividend after 1, then repeat: 16 / 15

Going ahead to step 6:
The number 15 fits into 16 1 times, leaving a remainder of 1.
Write down 1 as next digit of the result. 
Result so far: 8391.0
Subtracting 15 from 16 leaves us with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Step 7:
10 divided by 15 is 0 with a remainder of 10.
Put 0 as the next digit of the answer. 
Result so far: 8391.0
Deduct 0 from 10 and we're left with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 8:
15 goes into 100 6 times with a remainder of 10.
Use 6 as the next digit of our solution. 
Result so far: 8391.06
If we take 90 away from 100, we end up with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 9:
100 divided by 15 is 6 with a remainder of 10.
Use 6 as the next digit of our solution. 
Result so far: 8391.066
If we subtract 90 from 100, we get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

After the division, we end up with 8391.066 and a remainder of 0.001.