We divide 431239 by 3
We're looking to find how many times 3 goes into 431239.

Advancing to step 1:
When dividing 4 by 3, we get 1 with a remainder of 1.
Put 1 as the next digit of the answer. 
Result so far: 1.0
The remainder is 1 after subtracting 3 from 4.
Include the next digit (3) from the dividend after 1, then repeat: 13 / 3

Step 2:
3 goes into 13 4 times with a remainder of 1.
The number 4 becomes the next digit in our result. 
Result so far: 14.0
If we subtract 12 from 13, we get 1.
Bring next digit (1) of the dividend behind the 1 and repeat the process: 11 / 3

On to step 3:
3 goes into 11 3 times with a remainder of 2.
The number 3 becomes the next digit in our result. 
Result so far: 143.0
Subtracting 9 from 11 leaves us with 2.
Take the next digit (2) from the dividend and append it to 2, then repeat: 22 / 3

On to step 4:
The number 3 fits into 22 7 times, leaving a remainder of 1.
Put 7 as the next digit of the answer. 
Result so far: 1437.0
The remainder is 1 after subtracting 21 from 22.
Grab the next digit (3) from the dividend, add it to 1, then carry on: 13 / 3

Let's proceed to step 5:
If we divide 13 by 3, we get 4 and a remainder of 1.
The next digit of our result is 4. 
Result so far: 14374.0
Subtracting 12 from 13 leaves us with 1.
Append the next digit (9) from the dividend to 1 and continue with: 19 / 3

Advancing to step 6:
3 goes into 19 6 times with a remainder of 1.
Put 6 as the next digit of the answer. 
Result so far: 143746.0
Deduct 18 from 19 and we're left with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

On to step 7:
The number 3 fits into 10 3 times, leaving a remainder of 1.
The number 3 becomes the next digit in our result. 
Result so far: 143746.3
If we take 9 away from 10, we end up with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

On to step 8:
When dividing 10 by 3, we get 3 with a remainder of 1.
The number 3 becomes the next digit in our result. 
Result so far: 143746.33
Deduct 9 from 10 and we're left with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

The quotient of the division is 143746.33, and the remainder is 0.001.