Eureka!
Eureka: c. 1600, from Greek heureka “I have found (it),” first person singular perfect active indicative of heuriskein “to find.” Supposedly shouted by Archimedes (C. 287-212 B.C.E.) when he solved a problem that had been set to him: determining whether goldsmiths had adulterated the metal in the crown of Hiero II, king of Syracuse.