# Prove 1+1=2

• Feb 25th 2010, 12:53 PM
Mukilab
Prove 1+1=2
How to prove (not show) that 1+1=2
• Feb 25th 2010, 12:59 PM
Quacky
I'm not sure I understand. There is not a proof needed. Is that not almost the very definition of two?
• Feb 25th 2010, 01:14 PM
nikhil
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)
• Feb 25th 2010, 02:17 PM
Mukilab
Quote:

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)

Quote:

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.
• Feb 25th 2010, 02:53 PM
$x+x=(x+x)=2(x)$
$=$ means "what is before" is the same as "what is after".
If $x=1,$
$1+1=2(1)=2$