The expression is equal to $\displaystyle{{2}}^{{3}}\cdot{{6}}^{{-{{2}}}}\usepackage{cmbright}\Huge\$ . A negative exponent does mean that something is going into the denominator, but you have confused the two factors. The second factor can be rewritten as $\displaystyle\frac{{1}}{{{6}}^{{2}}}\usepackage{cmbright}\Huge\$

The negative in the second exponent does not apply to the factor $\displaystyle{{2}}^{{3}}\usepackage{cmbright}\Huge\$ .