We're dividing 80399893 by 646 
Our goal is to divide 80399893 by 646.

Going ahead to step 1:
646 can be fit into 8 0 times, resulting in a remainder of 8.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Deduct 0 from 8 and we're left with 8.
Take the next digit (0) from the dividend and append it to 8, then repeat: 80 / 646

On to step 2:
80 divided by 646 is 0 with a remainder of 80.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Deduct 0 from 80 and we're left with 80.
Fetch the next digit (3) from the dividend, attach it to 80 and continue: 803 / 646

Moving on to step 3:
When dividing 803 by 646, we get 1 with a remainder of 157.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
If we take 646 away from 803, we end up with 157.
Append the next digit (9) from the dividend to 157 and continue with: 1579 / 646

Moving on to step 4:
If we divide 1579 by 646, we get 2 and a remainder of 287.
Write down 2 as next digit of the result. 
Result so far: 12.0
Subtract 1292 from 1579 to get 287.
Grab the next digit (9) from the dividend, add it to 287, then carry on: 2879 / 646

Moving on to step 5:
The number 646 fits into 2879 4 times, leaving a remainder of 295.
Write down 4 as next digit of the result. 
Result so far: 124.0
If we subtract 2584 from 2879, we get 295.
Include the next digit (8) from the dividend after 295, then repeat: 2958 / 646

On to step 6:
If we divide 2958 by 646, we get 4 and a remainder of 374.
Use 4 as the next digit of our solution. 
Result so far: 1244.0
If we take 2584 away from 2958, we end up with 374.
Take the next digit (9) from the dividend and append it to 374, then repeat: 3749 / 646

Let's proceed to step 7:
646 goes into 3749 5 times with a remainder of 519.
The number 5 becomes the next digit in our result. 
Result so far: 12445.0
Subtracting 3230 from 3749 leaves us with 519.
Bring next digit (3) of the dividend behind the 519 and repeat the process: 5193 / 646

Step 8:
5193 divided by 646 is 8 with a remainder of 25.
The next digit of our result is 8. 
Result so far: 124458.0
Subtract 5168 from 5193 to get 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

Let's proceed to step 9:
646 can be fit into 250 0 times, resulting in a remainder of 250.
Put 0 as the next digit of the answer. 
Result so far: 124458.0
Subtracting 0 from 250 leaves us with 250.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2500, and continue the process.

Let's proceed to step 10:
When dividing 2500 by 646, we get 3 with a remainder of 562.
Record the quotient 3 as the next digit in the result. 
Result so far: 124458.03
The remainder is 562 after subtracting 1938 from 2500.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5620, and continue the process.

On to step 11:
5620 divided by 646 is 8 with a remainder of 452.
The number 8 becomes the next digit in our result. 
Result so far: 124458.038
If we subtract 5168 from 5620, we get 452.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4520, and continue the process.

Let's proceed to step 12:
646 can be fit into 4520 6 times, resulting in a remainder of 644.
The number 6 becomes the next digit in our result. 
Result so far: 124458.0386
Subtracting 3876 from 4520 leaves us with 644.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6440, and continue the process.

Advancing to step 13:
6440 divided by 646 is 9 with a remainder of 626.
The next digit of our result is 9. 
Result so far: 124458.03869
The remainder is 626 after subtracting 5814 from 6440.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6260, and continue the process.

Let's proceed to step 14:
646 can be fit into 6260 9 times, resulting in a remainder of 446.
Use 9 as the next digit of our solution. 
Result so far: 124458.038699
Deduct 5814 from 6260 and we're left with 446.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4460, and continue the process.

The final result is 124458.038699 with a remainder of 4.46e-05.