# What does E mean in 9.0122222900391E-5? [closed]

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?

• 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. Aug 25, 2011 at 23:21
• @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 $42+22=64$... Nov 12, 2011 at 20:37
• 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... May 8, 2012 at 12:00
• How in the world does this have 12K views?
– user641
Mar 12, 2013 at 1:37
• How does this page have 125K views now?? Dec 28, 2015 at 5:32

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

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

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

• if -5 is positive, it's multiplication? it's only division when -5 is a negative like -5?? Nov 18, 2018 at 20:46
• Yes, that's correct. 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.