"Q.E.D." (sometimes written "QED") is an abbreviation for the Latin phrase "quod erat demonstrandum" ("that which was to be demonstrated"), a notation which is often placed at the end of a mathematical proof to indicate its completion. Several symbols are occasionally used as synonyms for Q.E.D. These include a filled square (Unicode U+220E, as used in Mathematics Magazine and American Mathematical Monthly), a filled rectangle (Knuth 1997, pp. 3 and 39), or an empty square .

See also

Proof, Q.E.F.

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References

Knuth, D. E. The Art of Computer Programming, Vol. 1: Fundamental Algorithms, 3rd ed. Reading, MA: Addison-Wesley, pp. 3 and 39, 1997.

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Q.E.D.

Cite this as:

Weisstein, Eric W. "Q.E.D.." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/QED.html

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