The number of sides of a regular polygon, whose each exterior angle has a measure of 45^o, is _____.

We know that the measure of each exterior angle of a regular polygon is $\frac{{360}^{\mathrm{o}}}{\mathrm{n}}.$

Where ‘n’ is the number of sides of the polygon.

Given that, each exterior angle has a measure of 45^o.

Therefore, ${45}^o=\frac{{360}^o}{\mathrm{n}}$

$\Rightarrow \mathrm{n}=\frac{{360}^o}{{45}^o}$

$\Rightarrow \mathrm{n}=8$

Therefore, the number of sides of the given polygon is 8.