The Short Version
The claim that "the sum of 1 and 1 is equal to 3" is unequivocally false. Every credible mathematical source confirms that 1+1=2, a foundational truth proven rigorously from the Peano axioms and formal logic. Purported "proofs" of 1+1=3 rely on hidden errors like division by zero and are presented as tricks, not valid mathematics. The cultural metaphor of "1+1=3" (e.g., a couple having a child) is a figure of speech, not an arithmetic identity.