How do you solve this? $$2^{5^{2017}} \bmod 11$$ I tried my own method, and I got that: $$2^{5^{2017}} \equiv 10\pmod{11}$$ But I'm not sure it's the correct answer. Thanks!
I've read about Fermat's little theorem and generally how congruence works. But I can't figure out how to work out these two:   $13^{100} \bmod 7$ $7^{100} \bmod 13$   I've also heard of this formula:  $$a \equiv b\pmod n \Rightarrow a^k \equiv b^k \pmod n $$  But I don't see how exactly to use that here, because from $13^1 \bmod 7$ I get 6, and $13^2 \bmod 7$ is 1. I'm unclear as to which one to raise to the kth power here (I'm assuming k = 100?)  Any hints or pointers in the right direction would be great.
An explanation of Hawking Radiation I wish to select areas of a mesh, but it would be much simpler to just select the ones I don't want selected (because they are easier to access), and then inverse the selection.  Is this possible? I'm building a child theme and it currently has a very simple &lt;head&gt; section in header.php:  &lt;head&gt;   &lt;meta charset="&lt;?php bloginfo( 'charset' ); ?&gt;"&gt;   &lt;meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1"&gt;   &lt;title&gt;&lt;?php wp_title( '|', true, 'right' ); ?&gt;&lt;/title&gt;   &lt;link rel="profile" href="http://gmpg.org/xfn/11"&gt;   &lt;link rel="pingback" href="&lt;?php bloginfo( 'pingback_url' ); ?&gt;"&gt;   &lt;!--[if lt IE 9]&gt;   &lt;script type="text/javascript" src="&lt;?php echo get_template_directory_uri(); ?&gt;/js/html5shiv.min.js"&gt;&lt;/script&gt;   &lt;![endif]--&gt;    &lt;?php wp_head(); ?&gt; &lt;/head&gt;   I'm guessing wp_head() is responsible for the second &lt;title&gt; element (it appears just there in the final HTML), but other things I've read say this is impossible.  Should I be removing the &lt;title&gt; from my header.php, or should I be adding something to my functions to remove the title from wp_head() (eg. remove_action('wp_head', 'title') ?  Or should I be doing something else altogether? Occasionally, the Unicode character sequence U+200C U+200B (ZWNJ ZWSP) is inserted into comments In     ... the number "5000" does not paste as such but instead as  5 0 U+200C U+200B 0 0   The HTML source looks like this:  perhaps the easiest would be &lt;code&gt;\edef\tmp{\everypar{\widowpenalty\the\widowpenalty\relax}}\tmp\widowpenalty=-50&amp;zwnj;&amp;#8203;00&lt;/code&gt; that may reset   Or (smaller snippet):  \widowpenalty=-50&amp;zwnj;&amp;#8203;00&lt;/code&gt; that   So in the HTML, we have extraneous &amp;zwnj; and &amp;#8203; in between the two middle digits of 5000.  Upon pasting and trying out this code, this first led to a mysterious compiler error. The same issue happened within a (now deleted) comment thread below ; there, these or similar two characters were inserted after the letter "r" within the string \ref ("\ref").  Note that not all browsers wrap the same way. The above screenshot was for Firefox 19.0.2, in which it breaks between \relax}} and \tmp, with 5000 insidiously left intact on the second line but with the two special characters remaining in the middle. So that is why this took me completely by surprise. Other browsers might indeed only break on the invisible Unicode characters, such as Chrome 25:    Or on a smaller screen with the mobile site, multiple line breaks might show, possibly still leaving the Unicode characters unused: modify specific column with sed or awk I have a CSV file that looks like this:  qw12er,foo,0 bn5mgh rt8yp,foo,10 gh78jk bn852mv,foo,852 78ghjkh tgbr,foo,10 ujmyhn wsx2d,foo,0000 ui52ohn tgbr,foo,7418529 ujmyhn ikl896o,foo,22 wsxdc52   I want to modify the 3rd column and remove all numbers and space from the beginning of the 3rd column.  Then output would be as follows:  qw12er,foo,bn5mgh rt8yp,foo,gh78jk bn852mv,foo,78ghjkh tgbr,foo,ujmyhn wsx2d,foo,ui52ohn tgbr,foo,ujmyhn ikl896o,foo,wsxdc52 Why are there two Address lines in Address forms? Experience and a quick Google Images search suggests that it's standard to provide two fields for Address/Street. A colleague argues that it's perceived as two alternative addresses, and that the fact that there's only one country, state, zip, phone just makes it more confusing. I tried to think of a good explanation for having two fields but couldn't. To the reason of "there are some very long addresses" he replies "then why don't they use a multiline input field which would make it clearer that it's the same address".  So, what's the reason? And is it only standard for the US or for Europe as well? How to copy all files from a directory to a remote directory using scp? Disabling submit-button until the user has completed the form How do you think about disabling the submit-button until the user has completed the form or the required fields?   I find similar questions here on ux.se and somebody answered that the user will think that the form is broken or not immediately realize whats going on.  I think hiding is not that good but a disabling (e.g. grayscale, opacity, ...) plus a short text in the button would improve usability because the user realise that he still has to fill out something.  Is there anybody with experience or examples besides the usual error-messages/validation after submitting? Prevent Adobe Reader from switching to "Fit Page" zoom when bookmark is clicked When I cut a layer using marquee tool, I get blur edges to cut side. How do I get sharp edges after cut? I am using rectangular marquee tool to cut a portion of the layer in photoshop cs5, but after cutting, the edges are not sharp, I get blur edges.      how can I get sharp edges? Error "WIF10201: No valid key mapping found" when trying to create claims from SAML What does "Meta" mean? I am fairly new to Stack Overflow and just stumbled across Meta Stack Overflow.  I can't seem to figure out what the purpose of the "Meta" site is. Can someone please explain it to me? Node Package Manager got corrupted in some way, now it cannot be installed Direction of friction when a car turns Delete all files except specified files/folders using command line? I have a folder containing a lot of folders and different files with the following structures :  NASA │ ├── a │   ├── doc1 │   ├── doc2 │   ├── doc3 │   ├── folder1 │   └── folder2 │ ├── b │   ├── doc1 │   ├── doc2 │   ├── doc3 │   ├── folder1 │   └── folder2 │ ├── c │   ├── doc1 │   ├── doc2 │   ├── doc3 │   ├── folder1 │   └── folder2 │ ├─ x ├─ y └─ z          I want to delete the content of the folder (NASA/) except specified folders and files.   For example I want to keep a folder, b folder and x file.     I tried   :   rm !(a/) -r NASA/   And (as explained in the answer ):  find NASA/ -type f ! -iname "x" -delete   But this is not very straight forward and I have to use a bash script.    Am I missing a more easy way ? How can I do this in a single command? How can I find the product key of Office 2011 after restoring from backup? I had to restore my iMac from a Time Machine backup.  Everything seemed fine until I tried to start Office 2011 and it is asking me to re-enter my product key. I am trying to locate my key (I believe I downloaded this version originally and it should be in my email but I can't find it)  I tried a program that is supposed to "find the keys for products installed on your computer" (Mac Product Key Finder) and it found my very old Office 2008 key, but not 2011.  I am surprised that if I had a totally working install before recovering from back-up that this wasn't restored as well - do I have any options to find it hiding somewhere on my drive?  Note: The recovery was after a hard drive was replaced by the Apple store - if that makes a difference, so this is a new internal drive. In the following code, I need to use +/- where I have used it, and plus/minus where I have used it.  \documentclass{amsart} \usepackage{lipsum} \usepackage{calc} \parindent=0 pt \parskip=12 pt plus 0 pt minus 0 pt \def\headsep{25pt} \newcommand{\LAYOUT}[5]{%   \setlength{\hoffset}{0pt}   \setlength{\voffset}{0pt}   \setlength{\topmargin}{#1 - 1in - \voffset - \headheight - \headsep}    \setlength{\oddsidemargin}{#2 - 1in - \hoffset}   \setlength{\evensidemargin}{\oddsidemargin}   \setlength{\textheight}{#3}   \setlength{\textwidth}{#4}   \setlength{\marginparwidth}{#5} } \newcommand{\FULLPAGE}{\LAYOUT{1in}{1in}{9in}{6.5in}{0.75in}}  \FULLPAGE \begin{document} \lipsum[1-10] \end{document}   If I replace the plus and minus in line 5 with + and - I get an enigmatic  "missing begin{document}" error.    If I replace the minus's in lines 10-11 with "-" I get an equally enigmatic error:  "Missing number, treated as zero. Illegal unit of measure (pt inserted)."   Can somebody please explain when one can use +/- and when one can use plus/minus?  Presumably there's a good reason why latex's error messages are so completely mystifying, and why inconsistencies like these keep appearing? It's really hard to explain to my coauthors, who regularly complain that latex is the most infuriating program ever devised by mankind.  Thanks very much for any advice!   Leo Can a warlock use one of their Thirsting Blade attacks to grapple or shove? If I build a package from source how can I uninstall or remove completely? I used source code to build one package such as below:  ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var --libexecdir=/usr/lib --with-package-name="Myplugin" --with-package-origin="http://www.ubuntu.org/" --enable-gtk-doc --disable-static make make install   But unfortunately, i discovered that its the latest version, and has lot of bugs, so i need to remove it/uninstall it. But how can i do so? I tried make clean; make uninstall but still i see it exist:  # pkg-config --list-all | grep Myplugin myplugin-.... $ ls /usr/lib/myplugin/libXYZ.so exist....   How do you remove this now? I'm connecting to some enterprise wireless network (eduroam).  The thing is that it saves the User/Password in the wireless settings, anyone can click 'Show password' and see my university account password.  What I want is that it prompts me everytime the credentials inputs when I try to connect to the network and don't save it under the 'settings' page.  Is this possible? If yes, how?  Thanks  Ubuntu 18.04 LTS