How do you format a logarithm's base in Stack Exchange? [closed]

How would you type log [base] (4) in stack exchange?

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$\log_4(4)$...\log_4(4) in dollar signs –  David Mitra Nov 9 '11 at 10:54
Is it the correct place to ask this question? –  user13838 Nov 9 '11 at 10:55
–  Grigory M Nov 9 '11 at 10:57
Thank you that will be very usefull –  Rollo Nov 9 '11 at 11:06
$\log_2 4$ converts to $\log_2 4$