3990639 ÷ 310 
We're looking to find how many times 310 goes into 3990639.

Moving on to step 1:
When dividing 3 by 310, we get 0 with a remainder of 3.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we subtract 0 from 3, we get 3.
Fetch the next digit (9) from the dividend, attach it to 3 and continue: 39 / 310

On to step 2:
The number 310 fits into 39 0 times, leaving a remainder of 39.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 39 after subtracting 0 from 39.
Bring next digit (9) of the dividend behind the 39 and repeat the process: 399 / 310

Moving on to step 3:
310 goes into 399 1 times with a remainder of 89.
Write down 1 as next digit of the result. 
Result so far: 1.0
Subtracting 310 from 399 leaves us with 89.
Append the next digit (0) from the dividend to 89 and continue with: 890 / 310

Moving on to step 4:
310 goes into 890 2 times with a remainder of 270.
Write down 2 as next digit of the result. 
Result so far: 12.0
Subtracting 620 from 890 leaves us with 270.
Take the next digit (6) from the dividend and append it to 270, then repeat: 2706 / 310

Advancing to step 5:
When dividing 2706 by 310, we get 8 with a remainder of 226.
The next digit of our result is 8. 
Result so far: 128.0
Deduct 2480 from 2706 and we're left with 226.
Take the next digit (3) from the dividend and append it to 226, then repeat: 2263 / 310

Let's proceed to step 6:
When dividing 2263 by 310, we get 7 with a remainder of 93.
Write down 7 as next digit of the result. 
Result so far: 1287.0
The remainder is 93 after subtracting 2170 from 2263.
Append the next digit (9) from the dividend to 93 and continue with: 939 / 310

Step 7:
The number 310 fits into 939 3 times, leaving a remainder of 9.
Write down 3 as next digit of the result. 
Result so far: 12873.0
Subtract 930 from 939 to get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Going ahead to step 8:
The number 310 fits into 90 0 times, leaving a remainder of 90.
The number 0 becomes the next digit in our result. 
Result so far: 12873.0
Subtracting 0 from 90 leaves us with 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 900, and continue the process.

Going ahead to step 9:
The number 310 fits into 900 2 times, leaving a remainder of 280.
The number 2 becomes the next digit in our result. 
Result so far: 12873.02
If we subtract 620 from 900, we get 280.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2800, and continue the process.

Moving on to step 10:
2800 divided by 310 is 9 with a remainder of 10.
Record the quotient 9 as the next digit in the result. 
Result so far: 12873.029
Subtracting 2790 from 2800 leaves us with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Let's proceed to step 11:
100 divided by 310 is 0 with a remainder of 100.
Use 0 as the next digit of our solution. 
Result so far: 12873.029
Deduct 0 from 100 and we're left with 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1000, and continue the process.

Moving on to step 12:
If we divide 1000 by 310, we get 3 and a remainder of 70.
The next digit of our result is 3. 
Result so far: 12873.02903
If we take 930 away from 1000, we end up with 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

Moving on to step 13:
When dividing 700 by 310, we get 2 with a remainder of 80.
Put 2 as the next digit of the answer. 
Result so far: 12873.029032
If we subtract 620 from 700, we get 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

Advancing to step 14:
310 goes into 800 2 times with a remainder of 180.
The number 2 becomes the next digit in our result. 
Result so far: 12873.0290322
Subtracting 620 from 800 leaves us with 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1800, and continue the process.

The quotient of the division is 12873.0290322, and the remainder is 1.8e-06.