A negative exponent does not mean that the number is negative. The first factor is $\displaystyle{{2}}^{{-{4}}}\usepackage{cmbright}\Huge\$ , which equals $\displaystyle\frac{{1}}{{{2}}^{{4}}}\usepackage{cmbright}\Huge\$

The correct answer is: $\displaystyle\frac{{1}}{{16}}\usepackage{cmbright}\Huge\$