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All I know is that I can do log(number) to get log base ten and ln(number) to get log base e. How can I insert logarithms with other bases in Google Calculator? I can't seem to figure it out.

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    $\begingroup$ you can use $\log_a b = \frac{\ln b}{\ln a}$ $\endgroup$ – Jane Mar 24 '17 at 1:17
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    $\begingroup$ @Jane That's probably as complete an answer as is possible for this question, so perhaps it's worth promoting it from a comment to an answer? $\endgroup$ – Travis Willse Mar 24 '17 at 1:23
  • $\begingroup$ Nice math! Good to know, but is there a more direct route? $\endgroup$ – Aaron Franke Mar 24 '17 at 1:23
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    $\begingroup$ The Google Guide Quick Reference says that lg for $log_2$ is available in addition to log and ln, but those are the only ones. $\endgroup$ – rogerl Mar 24 '17 at 1:30
  • $\begingroup$ @Travis that's ok! at least it's helpful :) $\endgroup$ – Jane Mar 25 '17 at 1:43
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For base $b=10$ we can use log_10(n) or log(n)

For base $b=e$ we can use ln(n)

For base $b=2$ we can use log_2(n) or lg(n)

Other bases aren't implemented, so we use the Change of Base Rule, namely $\log_b(n) = \frac{\ln(n)}{\ln(b)}$ which we put into the calculator as ln(n)/ln(b). This works with any other base, so log(n)/log(b) would be the same.

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Google calculator now supports arbitrary bases. For $\log_2(16)$, for example, you may now enter log2(16).

Screenshot of Google calculator

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    $\begingroup$ This doesn't work for arbitrary bases. log8(4) is interpreted as log(8) * 4 $\endgroup$ – Aaron Franke Oct 7 '19 at 4:52
  • $\begingroup$ @aaron You are right. Apologies, I assumed this would work for any base; appears to only work for base 2. $\endgroup$ – pgayed Oct 8 '19 at 7:29
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You can input it into the Google search bar like this, log_base(x) would be written as:

log(x,base)

For example, log base 11 of 4 (or log_11(4) ) would look like this:

log(4,11)

As for Google calculator... not sure yet.

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  • $\begingroup$ This is wrong. Google treats the comma as a decimal point here. You can tell because log(4,0) is equal to log(4). $\endgroup$ – Aaron Franke May 15 '20 at 9:22

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