Q: How can we prove that 2+2 always equals 4?

6 Responses to Q: How can we prove that 2+2 always equals 4?

1. Nathan Goedeke says:

   February 9, 2011 at 10:21 pm

   What would happen if the Parallel Postulate became the Parallel Theorem? Would it only effect the scientific community in a hypothetical sense or would there be more drastic implications?
2. Vishal Agarwal says:

   May 30, 2011 at 11:31 am

   why we not multiply any trigonometry question by zero to solve it..
   example- prove 2+2 =4
   o*(2+2) = 4 * 0
   0 = 0
   please answer ……….
3. The Physicist says:

   May 30, 2011 at 1:04 pm

   Although you end up with a true statement (0=0), you don’t get any new information.
   For example, if you were stuck with a question like “2x+1=5, what is x?”, you could multiply both sides by zero and get the (true) statement “0=0″, but you still wouldn’t know what x is.
4. sharafali.a says:

   February 24, 2012 at 4:50 am

   X+X+X+X=(X+X)+(X+X)
   4X=2X+2X ………sice; iknow mango=mango=2mango
   or 4X=X(2+2)
   devide this by X => 4=2+2
   or 2+2=4

   hence the proof.
5. bounce says:

   February 27, 2012 at 3:11 pm

   sharafali.a, if you’re really intent on providing a proof, you could use the definitions directly instead of involving multiplication, division, distribution, and a variable. 4=1+1+1+1=(1+1)+(1+1)=2+2. Hardly deserves to be called a proof.

   vishal, deriving a true fact from an initial statement does not prove the initial statement. This is backwards. I can use that type of argument to “prove” almost anything:

   2+2 = 3
   o*(2+2) = 3 * 0
   0 = 0
6. Locutus says:

   April 22, 2012 at 12:24 am

   In science, theories are often not proven, but disproven. Perhaps the same concept would have to be applied here. If the numbers 0 through 4 are set quantities (so that I can’t just turn around and say, oh let’s make 2=3 (artificially, as in a linguistic change, not a mathematical one)), then by definition a physical total of two 2s would yield four. It may be impossible to prove that 2+2 always yields four, but perhaps it is impossible to disprove 2+2 equalling four ever. Because the physical evidence is overwhelmingly in 2+2=4′s favor, perhaps it is a postulate or observing type of thing, like right angles are always equal, not a proof type of thing. However, applying the Peano axioms, there is a proof. There is one listed here: http://skepticsplay.blogspot.com/2008/12/224-proof.html. Whether or not this actually proves 2+2=4 for every case is another matter.

   Regardless, unless if you can find an instance where two physical twos never make a physical four (and I don’t mean taking two sets of two black holes and combining them together to see if you end up with four black holes or something to that effect, count before you combine them), 2+2=4.

   I like pi(e).