Six nines in pi

A sequence of six consecutive nines occurs in the decimal representation of the number pi (π), starting at the 762nd decimal place.^[1][2] It has become famous because of the mathematical coincidence, and because of the idea that one could memorize the digits of π up to that point, and then suggest that π is rational. The earliest known mention of this idea occurs in Douglas Hofstadter's 1985 book Metamagical Themas, where Hofstadter states^[3][4]

I myself once learned 380 digits of π, when I was a crazy high-school kid. My never-attained ambition was to reach the spot, 762 digits out in the decimal expansion, where it goes "999999", so that I could recite it out loud, come to those six 9s, and then impishly say, "and so on!"

This sequence of six nines is sometimes called the "Feynman point",^[5] after physicist Richard Feynman, who allegedly stated this same idea in a lecture.^[6] However it is not clear when, or even if, Feynman made such a statement. It is not mentioned in published biographies or in his autobiographies, and is unknown to his biographer, James Gleick.^[7]