Estimate a common formula

I know this should be easy, but I just can't find the proper search result. Thanks.

$\left(1-\frac1n\right)^n$, what is the estimation value when $n$ is very large?

Some follow-up,

If $n = 100$, what is the formula to calculate this?

• Define "estimation". I know that for large, large $\;n\;$ a pretty good estimation is $\;e^{-1}\;$ ... – DonAntonio Sep 18 '13 at 23:55
• I've never heard of an "estimation value" but $\lim_{n \to \infty} (1- 1/n)^n = 1/e$, so $(1- 1/n)^n$ is close to $1/e$ if $n$ is large and positive. This is a standard calculus exercise. – Stefan Smith Sep 18 '13 at 23:59

The estimation value when n is very large is $1/e$, where $e$ is the well known mathematical constant.
Therefore, what you are seeking is $e^{-1}$, or $1/e$.