A sequence of six 9's occurs in the decimal representation of the number pi, starting at the 762nd decimal place. It has become famous because of the mathematical coincidence and because of the idea that one could memorize the digits of up to that point, recite them and end with "nine nine nine nine nine nine and so on", which seems to suggest that is rational. The earliest known mention of this idea occurs in Douglas Hofstadter's 1985 bookMetamagical Themas, where Hofstadter states This sequence of six nines is sometimes called the "Feynman point", after physicist Richard Feynman, who allegedly stated this same idea in a lecture. It is not clear when, or even if, Feynman made such a statement, however; it is not mentioned in published biographies or in his autobiographies, and is unknown to his biographer, James Gleick.
Related statistics
is conjectured to be, but not known to be, a normal number. For a normal number sampled uniformly at random, the probability of a specific sequence of six digits occurring this early in the decimalrepresentation is about 0.08%. However, if the sequence can overlap itself then the probability is less. The probability of six 9's in a row this early is about 10% less, or 0.0686%. The early string of six 9's is also the first occurrence of four and five consecutive identical digits. The next sequence of six consecutive identical digits is again composed of 9's, starting at position 193,034. The next distinct sequence of six consecutive identical digits starts with the digit 8 at position 222,299, while strings of nine 9's next occur at position 590,331,982 and 640,787,382. The positions of the first occurrence of a string of 1, 2, 3, 4, 5, 6, 7, 8, and 9 consecutive 9's in the decimal expansion are 5; 44; 762; 762; 762; 762; 1,722,776; 36,356,642; and 564,665,206, respectively.
Decimal expansion
The first 1,001 digits of , showing consecutive runs of three or more digits including the consecutive six 9's underlined, are as follows:
