Explanation:
That is so because 1/3 is *not exactly equal to* 0.333333
0.333333 is an approximation of 1/3 which is correct to 6 decimal places.
So 0.333333 x 3 = 0.999999 which is approximately equal to 1.
If you want to be more accurate, you could write the fraction 1/3 everywhere and not write it in floating point form.
1/3 in floating point format will be 0.333333333…..and so on with infinite decimal places. This is because when you try to divide 1 by 3, you get a nonterminating recurring number after decimal point.
Its usually represented by a bar or dot on top of the recurring part
Ex. 1/3 = 0.3bar
(Sorry I can't get the bar on 3 by typing from keyboard)
But let's just say 0.3 bar is 0.333333…and so on to infinity.
When you multiply 0.3bar x 3 you get 0.9bar
= 0.999999….and so on to infinity.
These decimal point figures just a very great approximations of the fraction 1/3.
Hope this helps. Feel free to reply if you still have doubts.