Division by 3 does not exist

Think about it... how can you have 3 equal parts of an object? The decimate representation is impossible and one side always has to be bigger then the other. This is also why there is no such thing as 360 equal degrees in a circle as one degree has to be off by a little bit... There are no 360 numbers that will add up to 1 whole object either.

>>105
Infinitely close is the same as equals, go take some high school math classes if you don't understand.  For example, if you used a tool with finite precision to measure something with the value 5, you only know that it is close to 5 within that precision; you cannot actually prove that it is 5.  As the precision approaches infinity, you can prove that it is closer and closer to 5, and finally at infinite precision, you know for a fact that the value is equal to 5.