I often find this at the bottom of pages.

Page generated in 0.00013899803161621

Sometimes, I come across

Page generated in 9.0122222900391E-5

What does that time mean?

I tried searching Wikipedia for E and maths but found the e mathematical constant. My guess is E stand for Exponential and -5 is the power it is raised to. And the displayed time is a really small number. But that doesn't make sense when compared to the other time in the question. 0.00013899803161621 is bigger than 9.0122222900391E-5.

If it means x times $10^{-5}$, then 9.0122222900391E-5 will be 0.000090122222900391 which is smaller than 0.00013899803161621. What does E stand for?

  • 7
    $\begingroup$ In case anyone knows: where is this particular number coming from? There are a large number of google hits for it, many of which are not mirrors of this site, whereas (unsurprisingly) if I change the last decimal place by 1 in either direction there are no hits at all. $\endgroup$ Aug 25, 2011 at 23:21
  • 10
    $\begingroup$ @Michael, for whatever it's worth it is the multiple of $10^{-18}$ that is closest to $189\times 2^{-21}$. Google also knows various multiples of $2^{-22}$ to a similar precision. They all seem to be values related to timing. Possibly related, I have come across a bug in some versions of Linux whereby the system time would be off by exact multiples of $\frac{2^{42}}{10^{9}}$ seconds. Notice that $42+22=64$... $\endgroup$ Nov 12, 2011 at 20:37
  • 1
    $\begingroup$ So it is really a computer question, not a math question. If you want something other than wild speculation to the supplementary question "what does the E stand for?" you should try a computer site... $\endgroup$
    – GEdgar
    May 8, 2012 at 12:00
  • 5
    $\begingroup$ How in the world does this have 12K views? $\endgroup$
    – user641
    Mar 12, 2013 at 1:37
  • 1
    $\begingroup$ How does this page have 125K views now?? $\endgroup$
    – Nayuki
    Dec 28, 2015 at 5:32

3 Answers 3


It means $9.0122222900391\times 10^{-5}$. This is known as "scientific notation".

  • 2
    $\begingroup$ Is the E an abbreviation for something? $\endgroup$
    – Rasmus
    Oct 7, 2010 at 16:29
  • 9
    $\begingroup$ On calculators that E is sometimes denoted "exp", which is short for "exponential". In fact, "exponential notation" is another name for "scientific notation" $\endgroup$
    – Andy
    Oct 7, 2010 at 16:33
  • 2
    $\begingroup$ Well, only mathematicians the following is true: "Thou shalt not have another base before e", right? ;) $\endgroup$
    – Andy
    Oct 7, 2010 at 16:59
  • 13
    $\begingroup$ @AD.: I was really confused for a while, until I realized that you meant $\log_{10}$ rather than $\log_1 0$. :-) $\endgroup$ Oct 8, 2010 at 11:28
  • 2
    $\begingroup$ @Hans Lundmark: Of course, sorry :) $\endgroup$ Oct 9, 2010 at 4:41

E-5 just means x 10^(-5) i.e. divided by 100000

  • $\begingroup$ if -5 is positive, it's multiplication? it's only division when -5 is a negative like -5?? $\endgroup$
    – oldboy
    Nov 18, 2018 at 20:46
  • $\begingroup$ Yes, that's correct. $\endgroup$
    – Toby Mak
    Sep 12, 2019 at 12:35

I have always taken the E or e to mean "exponent of 10." This construction parses in all modern computing languages as an IEEE754 double or single precision number.


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