399972 divided by 3 
Our goal is to divide 399972 by 3.

Let's proceed to step 1:
3 goes into 3 1 times with a remainder of 0.
The next digit of our result is 1. 
Result so far: 1.0
Subtract 3 from 3 to get 0.
Take the next digit (9) from the dividend and append it to 0, then repeat: 9 / 3

On to step 2:
If we divide 9 by 3, we get 3 and a remainder of 0.
Write down 3 as next digit of the result. 
Result so far: 13.0
The remainder is 0 after subtracting 9 from 9.
Bring next digit (9) of the dividend behind the 0 and repeat the process: 9 / 3

Let's proceed to step 3:
3 can be fit into 9 3 times, resulting in a remainder of 0.
Put 3 as the next digit of the answer. 
Result so far: 133.0
If we take 9 away from 9, we end up with 0.
Grab the next digit (9) from the dividend, add it to 0, then carry on: 9 / 3

Advancing to step 4:
3 can be fit into 9 3 times, resulting in a remainder of 0.
The next digit of our result is 3. 
Result so far: 1333.0
Subtract 9 from 9 to get 0.
Bring next digit (7) of the dividend behind the 0 and repeat the process: 7 / 3

Let's proceed to step 5:
The number 3 fits into 7 2 times, leaving a remainder of 1.
Use 2 as the next digit of our solution. 
Result so far: 13332.0
Deduct 6 from 7 and we're left with 1.
Bring next digit (2) of the dividend behind the 1 and repeat the process: 12 / 3

On to step 6:
When dividing 12 by 3, we get 4 with a remainder of 0.
Record the quotient 4 as the next digit in the result. 
Result so far: 133324.0
If we subtract 12 from 12, 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.

Going ahead to step 7:
3 goes into 0 0 times with a remainder of 0.
The next digit of our result is 0. 
Result so far: 133324.0
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.

Let's proceed to step 8:
3 goes into 0 0 times with a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 133324.0
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.

The final outcome is 133324.0, with a leftover of 0.0.