The expression is equal to $\displaystyle{{5}}^{{-{{3}}}}\cdot{{3}}^{{2}}\usepackage{cmbright}\Huge\$ . A negative exponent does mean that something is going into the denominator, but you have confused the two factors. The first factor can be rewritten as $\displaystyle\frac{{1}}{{{5}}^{{3}}}\usepackage{cmbright}\Huge\$ . The negative in the first exponent does not apply to the factor $\displaystyle{{3}}^{{2}}\usepackage{cmbright}\Huge\$ .