We're dividing 421209 by 15 
Our goal is to divide 421209 by 15.

Step 1:
4 divided by 15 is 0 with a remainder of 4.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 4 leaves us with 4.
Grab the next digit (2) from the dividend, add it to 4, then carry on: 42 / 15

Going ahead to step 2:
42 divided by 15 is 2 with a remainder of 12.
Put 2 as the next digit of the answer. 
Result so far: 2.0
Deduct 30 from 42 and we're left with 12.
Append the next digit (1) from the dividend to 12 and continue with: 121 / 15

Advancing to step 3:
When dividing 121 by 15, we get 8 with a remainder of 1.
Use 8 as the next digit of our solution. 
Result so far: 28.0
The remainder is 1 after subtracting 120 from 121.
Bring next digit (2) of the dividend behind the 1 and repeat the process: 12 / 15

Moving on to step 4:
15 goes into 12 0 times with a remainder of 12.
The next digit of our result is 0. 
Result so far: 280.0
Subtracting 0 from 12 leaves us with 12.
Fetch the next digit (0) from the dividend, attach it to 12 and continue: 120 / 15

Advancing to step 5:
The number 15 fits into 120 8 times, leaving a remainder of 0.
Record the quotient 8 as the next digit in the result. 
Result so far: 2808.0
Deduct 120 from 120 and we're left with 0.
Grab the next digit (9) from the dividend, add it to 0, then carry on: 9 / 15

Moving on to step 6:
If we divide 9 by 15, we get 0 and a remainder of 9.
The next digit of our result is 0. 
Result so far: 28080.0
Deduct 0 from 9 and we're left 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.

Moving on to step 7:
If we divide 90 by 15, we get 6 and a remainder of 0.
Put 6 as the next digit of the answer. 
Result so far: 28080.6
If we subtract 90 from 90, we get 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 8:
0 divided by 15 is 0 with a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 28080.6
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.

Going ahead to step 9:
If we divide 0 by 15, we get 0 and a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 28080.6
Subtract 0 from 0 to get 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 quotient of the division is 28080.6, and the remainder is 0.0.