The simplest algorithms

As I was thinking about the algorithms, the simplest one I could think of is the 1+1=2 (If it counts as an algorithm)

Then I started to think, what if 1 plus 1 is not 2 anymore. Well, is there any other answers to 1 plus 1 instead of 2? Of course! 

If we put one pile of sand with another pile of sand, there will eventually be one pile of sand. In this case 1 plus 1 is 1. If we put a man and a woman together, we may get three persons after all (they have a baby). Thus 1 plus 1 is 3. Under binary number system, 1 plus 1 is 10.

Some answers can be somehow ridiculous, for example: one half circle plus another half circle is a whole circle (0), so 1 plus 1 is 0. 1 plus 1 equal to the Chinese character 王 (meaning “king”), if we rotates “1+1” 90 degree. If one cup of water and one cup of alcohol are poured together, the mixed liquid will be less than 2 cups. Therefore 1 plus 1 is smaller than 2.

Eventually, I find countless different answers to 1 plus 1, leading to another question: if the result is not certain, why do we need so-called "correct answers"?