The achievement may not rank up there with Samuel Morse's transmitting "What hath God wrought" from Washington, DC, to Baltimore in 1844 or Alexander Graham Bell's voice intoning, "Watson, come here. I want you" from one room to another in 1876. Nevertheless, scientists may eventually mark as a milestone the day in 2001 when Isaac Chuang and his colleagues at IBM determined that the two prime factors of the number 15 are three and five.

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