• change-of-base rule:$\log_ba = \frac{\log_xa}{\log_xb} = \frac{\log a}{\log b}$

• common logarithms:log with base $``10"$example: $\log3 = \log_{10}3$

example: $\log x = \log_{10}x$

• common logarithms:log with base $``10"$example: $\log3 = \log_{10}3$

example: $\log x = \log_{10}x$