A die is rolled 3 times. What is the probability that a five is rolled at least twice? The probability of not getting a five is $(\frac56)^3$, and I figure the probability of getting at least one 5 is $1-(\frac56)^3$, but I don't know how to figure out if it is rolled at least twice. Thoughts? Thanks in advance!

Since you're performing multiple experiments each with exactly two outcomes (the dice is a five vs. the dice is not a five), this is a classic example of a Bernoulli trial.
The standard formula to calculate the probability is then to use (from the Binomial distribution):
$$
P\{\text{that A occurs exactly k times in n trials}\} = \left( {\begin{array}{*{20}c} n \\ k \\ \end{array}} \right) p^k (1 - p)^{n-k}
$$
where event $A$ is the trial and $p$ is the probability for the success of a single trial ($\frac{1}{6}$).
In your case, you want to know the probability of it happening at least twice, so you need to sum the chances for it happening exactly twice and exactly three times:
$$
P\{\text{that A occurs exactly 2 times in 3 trials}\} + P\{\text{that A occurs exactly 3 times in 3 trials}\}
$$
Therefore,
$$
\begin{align}
P&= \left( {\begin{array}{*{20}c} 3 \\ 2 \\ \end{array}} \right) p^2 (1 - p)^{(3-2)} + \left( {\begin{array}{*{20}c} 3 \\ 3 \\ \end{array}} \right) p^3 (1 - p)^{(3-3)} \\
&= \left( {\begin{array}{*{20}c} 3 \\ 2 \\ \end{array}} \right) \cdot \frac{1}{6}^2 \cdot \frac{5}{6}^{1} + \left( {\begin{array}{*{20}c} 3 \\ 3 \\ \end{array}} \right) \cdot \frac{1}{6}^3 \cdot \frac{5}{6}^{0}\\
&= 3 \cdot \frac{1}{36} \cdot \frac{5}{6} + 1 \cdot \frac{1}{216} \cdot 1\\
&= \frac{15}{216} + \frac{1}{216}\\
&= \frac{16}{216}\\
&= \frac{2}{27} = 0,074... = 7,41 \% \\
\end{align}
$$
As you can see, this method of calculation can unfortunately become very tedious for larger examples, but it has the advantage of being a consistent approach for any problems surrounding Bernoulli trials. The intuitive approaches mentioned in some of the other answers can be quicker for small cases where all the possible outcomes can be manually considered.
