show that if $M \times \mathbb{R}^{n}$ is orientable than so is $M$

Question

I need to show if $M \times \mathbb{R}^{n}$ is orientable than so is $M$, where $M$ is connected manifold. $R^{n}$ has standard orientation (determined by standard basis ) and by the assumption $M \times \mathbb{R}^{n}$ also orienatable, so how to show that $M$ is orientable?