arithmetic – Formal proof for $(-1) times (-1) = 1$ – Mathematics …

July 24, 2026

Is there a formal proof for $(-1) \times (-1) = 1$? It’s a fundamental formula not only in arithmetic but also in the whole of math. Is there a proof for it or is it just assumed?

https://math.stackexchange.com/questions/304422/formal-proof-for-1-times-1-1

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arithmetic – formal proof for $(-1) times (-1) = 1$ – mathematics   [272] => arithmetic – formal proof for $(-1) times (-1) = 1$ – mathematics &#823o; [273] => arithmetic – formal proof for $(-1) times (-1) = 1$ – mathematics &#823p; [274] => arithmetic – formal proof for $(-1) times (-1) = 1$ – mathematics &#823-; [275] => arithmetic – formal proof for $(-1) times (-1) = 1$ – mathematics &#8230l [276] => arithmetic – formal proof for $(-1) times (-1) = 1$ – mathematics &#8230p [277] => arithmetic – formal proof for $(-1) times (-1) = 1$ – mathematics &#8230. ) </h1> </body>