I have got a Casio fx-82MS calculator, and I want to calcuate various logarithms with it, especially $\log₂(x)$-style logarithms. Unfortunately, its user interface contains buttons for just $\ln$ and $\log₁₀$.
How to do it with the existing set of buttons/commands?
According to David Mitra, $\log_a x={\ln x\over\ln a}$, what is absolutely usable for me.