**1.** The change of base formula for converting any logarithms to common logarithms (base 10)

$\log_{b}x$ = $\frac{\log_{10} x}{\log_{10} b}$

**2.** The change of base formula for converting any logarithms to natural logarithms (base e)

$\log_{b}x$ = $\frac{\log_{e} x}{\log_{e} b}$