1+1=1 ?

a=b let a=1 (meaning b=1 also)

then multiply 'a=b' by 'a', it will then give you

a²=ab

then da whole thing minus 'b²'

a²-b²=ab-b²

then factorize da thing and it becomes

(a+b)(a-b)=b(a-b)

finally, cut da (a-b) on both sides of da equation and its becomes

a+b=b >>>> which is equals to 1+1=1 since 'b' equals to 'a' and 'a' is '1' (see from top)

source from Jian Liang.

interesting eh? ^_____________^