Let's divide 643959 by 3
We're looking to find how many times 3 goes into 643959.

Advancing to step 1:
3 can be fit into 6 2 times, resulting in a remainder of 0.
Use 2 as the next digit of our solution. 
Result so far: 2.0
If we take 6 away from 6, we end up with 0.
Fetch the next digit (4) from the dividend, attach it to 0 and continue: 4 / 3

Moving on to step 2:
3 can be fit into 4 1 times, resulting in a remainder of 1.
The next digit of our result is 1. 
Result so far: 21.0
If we subtract 3 from 4, we get 1.
Fetch the next digit (3) from the dividend, attach it to 1 and continue: 13 / 3

Going ahead to step 3:
3 can be fit into 13 4 times, resulting in a remainder of 1.
Use 4 as the next digit of our solution. 
Result so far: 214.0
Deduct 12 from 13 and we're left with 1.
Append the next digit (9) from the dividend to 1 and continue with: 19 / 3

On to step 4:
19 divided by 3 is 6 with a remainder of 1.
Put 6 as the next digit of the answer. 
Result so far: 2146.0
Subtracting 18 from 19 leaves us with 1.
Grab the next digit (5) from the dividend, add it to 1, then carry on: 15 / 3

On to step 5:
3 can be fit into 15 5 times, resulting in a remainder of 0.
Use 5 as the next digit of our solution. 
Result so far: 21465.0
If we subtract 15 from 15, we get 0.
Bring next digit (9) of the dividend behind the 0 and repeat the process: 9 / 3

Going ahead to step 6:
If we divide 9 by 3, we get 3 and a remainder of 0.
Put 3 as the next digit of the answer. 
Result so far: 214653.0
Subtracting 9 from 9 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.

Step 7:
3 can be fit into 0 0 times, resulting in a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 214653.0
Subtract 0 from 0 to 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 8:
When dividing 0 by 3, we get 0 with a remainder of 0.
The next digit of our result is 0. 
Result so far: 214653.0
Subtract 0 from 0 to 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.

In conclusion, the division gives 214653.0 with a balance of 0.0.