# Math Help - Prove 1+1=2

1. ## Prove 1+1=2

How to prove (not show) that 1+1=2

2. I'm not sure I understand. There is not a proof needed. Is that not almost the very definition of two?

3. ## my thinking

I guess 1+1=2 is a convention.
if a single entity is called 1 (conventionally) then its double will be called 2(conventionally). since two quantities are individually single therfor 1+1=2 must hold. [for this operation of addition is also defined conventionally.]
this question is similar to the question why B comes after A.(even it is a convention)

4. Originally Posted by nikhil
I guess 1+1=2 is a convention.
if a single entity is called 1 (conventionally) then its double will be called 2(conventionally). since two quantities are individually single therfor 1+1=2 must hold. [for this operation of addition is also defined conventionally.]
this question is similar to the question why B comes after A.(even it is a convention)
Originally Posted by Quacky
I'm not sure I understand. There is not a proof needed. Is that not almost the very definition of two?
not what I was looking for. Will wait for further answers.

5. $x+x=(x+x)=2(x)$

A unit added to a unit is two of the same unit, by definition.
$=$ means "what is before" is the same as "what is after".

If $x=1,$

$1+1=2(1)=2$

This proof requires the definition that the "symbol" 2 represents two of the same unit,
whatever that unit may be.