How many ways are there to arrange $6$ beads of distinct colors in a $2 \times 3$ grid if reflections and rotations are considered the same? (In other words, two arrangements are considered the same if I can rotate and/or reflect one arrangement to get the other.)
There are $6! = 720$ ways to put the beads on the grid ignoring distinguishability. On the other hand, there are $4$ possible transformations of the board using rotations and reflections (including the identity):
\begin{tabular}{ccccccc}
A & B & C & & C & B & A\\
D & E & F & & F & E & D
\end{tabular}\begin{tabular}{ccccccc}
F & E & D & & D & E & F\\
C & B & A & & A & B & C
\end{tabular}None of these transformations besides the identity fixes an arrangement, so each arrangement is equivalent to three others. As a result, there are $\tfrac{720}{4} = \boxed{180}$ different arrangements.