Use the product property: $\displaystyle{\log}_{{b}}{\left({M}{N}\right)}={\log}_{{b}}{M}+{\log}_{{b}}{N}\usepackage{cmbright}\Huge\$

$\displaystyle{\log}_{{{10}}}{100}{d}={\log}_{{{10}}}{100}+{\log}_{{{10}}}{d}={2}+{\log}_{{{10}}}{d}\usepackage{cmbright}\Huge\$