how do you type in log base 3 of 16

On the web2.0calc calculator put it in as: log(16, 3) 

The result should give you: $${{log}}_{{\mathtt{3}}}{\left({\mathtt{16}}\right)}$$

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The  answer above is correct as well.

try putting it in as log16/log3

Thanks chilledz3non, I didn't know that - I'll have to try and remember it!