43990 ÷ 80 
Our goal is to divide 43990 by 80.

Step 1:
The number 80 fits into 4 0 times, leaving a remainder of 4.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 4, we get 4.
Grab the next digit (3) from the dividend, add it to 4, then carry on: 43 / 80

On to step 2:
If we divide 43 by 80, we get 0 and a remainder of 43.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 43 and we're left with 43.
Bring next digit (9) of the dividend behind the 43 and repeat the process: 439 / 80

Advancing to step 3:
439 divided by 80 is 5 with a remainder of 39.
Use 5 as the next digit of our solution. 
Result so far: 5.0
If we subtract 400 from 439, we get 39.
Append the next digit (9) from the dividend to 39 and continue with: 399 / 80

On to step 4:
80 goes into 399 4 times with a remainder of 79.
The number 4 becomes the next digit in our result. 
Result so far: 54.0
If we subtract 320 from 399, we get 79.
Bring next digit (0) of the dividend behind the 79 and repeat the process: 790 / 80

On to step 5:
790 divided by 80 is 9 with a remainder of 70.
Write down 9 as next digit of the result. 
Result so far: 549.0
If we subtract 720 from 790, we get 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

Going ahead to step 6:
The number 80 fits into 700 8 times, leaving a remainder of 60.
Record the quotient 8 as the next digit in the result. 
Result so far: 549.8
If we subtract 640 from 700, we get 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

On to step 7:
The number 80 fits into 600 7 times, leaving a remainder of 40.
Write down 7 as next digit of the result. 
Result so far: 549.87
Subtract 560 from 600 to get 40.
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 8:
If we divide 400 by 80, we get 5 and a remainder of 0.
The number 5 becomes the next digit in our result. 
Result so far: 549.875
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.

Going ahead to step 9:
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: 549.875
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.

Advancing to step 10:
The number 80 fits into 0 0 times, leaving a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 549.875
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.

Our division results in 549.875 with a remaining 0.0.