the gross-koblitz formula describes gauss sums on finite fieldsof characteristic $p$ in terms of the $p$-adic gamma function. thisformula is a $p$-adic lifting of stickelberger's congruence on gauss sums.there have been several proofs of the formula (gross-koblitz,dwork-boyarsky, katz, coleman), which all involve some cohomologicalcalculations. recently, a proof has been found by a. robert which isconceptual but truly elementary, at the level of "freshman $p$-adicanalysis." we will discuss robert's proof and describe possibleextensions