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**Mollier** Hi,

**problem: **

$\displaystyle \mathbb{Z}_p=\{0,1,\cdots,p-1\}$.

If $\displaystyle \alpha$ and $\displaystyle \beta$ are in $\displaystyle \mathbb{Z}_p$, let $\displaystyle \alpha+\beta$ be the least positive remainder obtained by dividing the (ordinary) sum of $\displaystyle \alpha$ and $\displaystyle \beta$ by $\displaystyle p$,

and similarly, let $\displaystyle \alpha\beta$ be the least positive remainder obtained by dividing the (ordinary) product of $\displaystyle \alpha$ and $\displaystyle \beta$ by $\displaystyle m$

Prove that if $\displaystyle \mathbb{F}$ is a field, then either the result of repeatedly adding $\displaystyle 1$ to itself is always different from $\displaystyle 0$,

or else the first time that it is equal to $\displaystyle 0$ occurs when the number of summands is a prime.

**attempt:**

I look at $\displaystyle n\cdot 1$ where $\displaystyle n$ is the number of times 1 is added to itself.

$\displaystyle n\cdot 1 (mod\;p)$, $\displaystyle p$ is prime since $\displaystyle \mathbb{Z}_p$ is a field.

$\displaystyle n\cdot 1 (mod\;p)=0$ when $\displaystyle n$ is a multiple of $\displaystyle p$, $\displaystyle n=\alpha p,\;n\in\mathbb{N}$.

For $\displaystyle n=1$, $\displaystyle 1 (mod\;p)\neq 0$.

For $\displaystyle n=\alpha p+1$, $\displaystyle \alpha p(mod\;p)+1(mod\;p)\neq 0$

I am really bad at this so any suggestion is very welcome!

Thanks