42309 ÷ 80 
We want to divide 42309 by 80.

Moving on to step 1:
When dividing 4 by 80, we get 0 with a remainder of 4.
Use 0 as the next digit of our solution. 
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 / 80

Advancing to step 2:
The number 80 fits into 42 0 times, leaving a remainder of 42.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 42 to get 42.
Include the next digit (3) from the dividend after 42, then repeat: 423 / 80

On to step 3:
80 can be fit into 423 5 times, resulting in a remainder of 23.
Put 5 as the next digit of the answer. 
Result so far: 5.0
If we take 400 away from 423, we end up with 23.
Bring next digit (0) of the dividend behind the 23 and repeat the process: 230 / 80

Going ahead to step 4:
80 goes into 230 2 times with a remainder of 70.
Write down 2 as next digit of the result. 
Result so far: 52.0
The remainder is 70 after subtracting 160 from 230.
Bring next digit (9) of the dividend behind the 70 and repeat the process: 709 / 80

Going ahead to step 5:
If we divide 709 by 80, we get 8 and a remainder of 69.
The next digit of our result is 8. 
Result so far: 528.0
Deduct 640 from 709 and we're left with 69.
Since there are no more digits in the dividend, we add a zero to the remainder making it 690, and continue the process.

Advancing to step 6:
80 goes into 690 8 times with a remainder of 50.
The number 8 becomes the next digit in our result. 
Result so far: 528.8
Subtract 640 from 690 to get 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

Moving on to step 7:
80 can be fit into 500 6 times, resulting in a remainder of 20.
Write down 6 as next digit of the result. 
Result so far: 528.86
Deduct 480 from 500 and we're left with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Advancing to step 8:
The number 80 fits into 200 2 times, leaving a remainder of 40.
The number 2 becomes the next digit in our result. 
Result so far: 528.862
The remainder is 40 after subtracting 160 from 200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

On to step 9:
80 can be fit into 400 5 times, resulting in a remainder of 0.
Record the quotient 5 as the next digit in the result. 
Result so far: 528.8625
Subtracting 400 from 400 leaves us 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.

On to step 10:
When dividing 0 by 80, we get 0 with a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 528.8625
If we subtract 0 from 0, 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.

Step 11:
If we divide 0 by 80, we get 0 and a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 528.8625
Deduct 0 from 0 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.

The final result is 528.8625 with a remainder of 0.0.