Is there a way to quickly calculate a log by hand? It needs to be "quick & dirty", much like other arithmetic done by hand (i.e. it doesn't have to be pretty, but needs to be quick and accurate, or at the very least, a very accurate estimate). The only thing I can think of is trial & error. But that doesn't seem terribly efficient, or accurate, to me. Not to mention you would need good "number sense", making your initial guesses very accurate and thus saving you time. So - what's the best way to do this? Say for example: Code (Text): log(7.0 x 10[SUP]-4[/SUP]) (10 to the power of what is equal to 7.0 x 10[SUP]-4[/SUP] ?) or Code (Text): -log(0.06) (10 to the power of what is equal to 1/0.06 ?) (In case you haven't guessed it - I need this skill largely for chemistry problems).