English

On the decimal and octal digits of $1/p$

Number Theory 2026-04-28 v6

Abstract

Let pp be a prime 3\equiv 3 mod 4, p>3p>3, and suppose that 10 has the order (p1)/2(p-1)/2 mod p. Then 1/p1/p has a decimal period of length (p1)/2(p-1)/2. We express the frequency of each digit 0,,90,\ldots,9 in this period in terms of the class numbers of two imaginary quadratic number fields. We also exhibit certain analogues of this result, so for the case that 10 is a primitive root mod pp and for the octal digits of 1/p1/p.

Keywords

Cite

@article{arxiv.2510.07873,
  title  = {On the decimal and octal digits of $1/p$},
  author = {Kurt Girstmair},
  journal= {arXiv preprint arXiv:2510.07873},
  year   = {2026}
}