250(1/2)^(10/2)

$${\mathtt{250}}{\mathtt{\,\times\,}}{\left({\frac{{\mathtt{1}}}{{\mathtt{2}}}}\right)}^{\left({\frac{{\mathtt{10}}}{{\mathtt{2}}}}\right)} = {\frac{{\mathtt{125}}}{{\mathtt{16}}}} = {\mathtt{7.812\: \!5}}$$

$$\\250(1/2)^{10/2}\\\\ =250*(\frac{1}{2})^5\\\\ =250*\frac{1}{32}\\\\ =\frac{125}{16}\\\\ =7\frac{13}{16}\\\\$$