128621 ÷ 15 
Our goal is to divide 128621 by 15.

Going ahead to step 1:
The number 15 fits into 1 0 times, leaving 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.
Take the next digit (2) from the dividend and append it to 1, then repeat: 12 / 15

Going ahead to step 2:
15 can be fit into 12 0 times, resulting in a remainder of 12.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 12, we end up with 12.
Take the next digit (8) from the dividend and append it to 12, then repeat: 128 / 15

Step 3:
When dividing 128 by 15, we get 8 with a remainder of 8.
Put 8 as the next digit of the answer. 
Result so far: 8.0
If we subtract 120 from 128, we get 8.
Grab the next digit (6) from the dividend, add it to 8, then carry on: 86 / 15

Step 4:
86 divided by 15 is 5 with a remainder of 11.
Use 5 as the next digit of our solution. 
Result so far: 85.0
The remainder is 11 after subtracting 75 from 86.
Include the next digit (2) from the dividend after 11, then repeat: 112 / 15

Advancing to step 5:
When dividing 112 by 15, we get 7 with a remainder of 7.
Use 7 as the next digit of our solution. 
Result so far: 857.0
Deduct 105 from 112 and we're left with 7.
Append the next digit (1) from the dividend to 7 and continue with: 71 / 15

Going ahead to step 6:
The number 15 fits into 71 4 times, leaving a remainder of 11.
The number 4 becomes the next digit in our result. 
Result so far: 8574.0
The remainder is 11 after subtracting 60 from 71.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

On to step 7:
110 divided by 15 is 7 with a remainder of 5.
Put 7 as the next digit of the answer. 
Result so far: 8574.7
Subtract 105 from 110 to get 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Advancing to step 8:
15 can be fit into 50 3 times, resulting in a remainder of 5.
The number 3 becomes the next digit in our result. 
Result so far: 8574.73
If we take 45 away from 50, we end up with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

On to step 9:
50 divided by 15 is 3 with a remainder of 5.
The next digit of our result is 3. 
Result so far: 8574.733
Deduct 45 from 50 and we're left with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Our division results in 8574.733 with a remaining 0.0005.