I know this question has been frequently asked but I can never seem to get it to work. Can you tell me what's wrong?  I have three divs within a #container div, which I want to centre side by side. The #container is 1000px wide (I want to keep it that way). Here is my code:    #container {   margin-top: 500px;   position: absolute;   width: 1000px; } .related-article {   background-color: #D6A400;   display: inline-block;   width: 230px;   height: 300px;   border-radius: 30px;   margin-bottom: 0px; } .related-article &gt; img {   width: 200px;   height: 150px;   border-radius: 15px;   margin-top: 15px; } .related-article &gt; h3 {   font-size: 15px;   width: 180px;   text-align: justify;   margin-left: auto;   margin-right: auto;   color: #f1f1f1;   font-family: Abel, serif;   margin-bottom: none; } a {   text-decoration: none; } #right {   float: right; } #left {   float: left; } #center {   margin-left: 385px;   margin-right: 385px; } &lt;div id="container"&gt;   &lt;h2&gt;Here's what you'll do!&lt;/h2&gt;   &lt;div id="left"&gt;     &lt;a href="#" class="related-article first" align="middle"&gt;       &lt;img src="download.jpeg" alt="T-rex"&gt;       &lt;h3&gt;Constructing amazing fossils you never even dreamed of&lt;/h3&gt;     &lt;/a&gt;   &lt;/div&gt;   &lt;div id="center"&gt;     &lt;a href="#" class="related-article second" align="middle"&gt;       &lt;img src="fossil-fish-10-lg.jpg" alt="Fish"&gt;       &lt;h3&gt;Studying ancient marine biology&lt;/h3&gt;     &lt;/a&gt;   &lt;/div&gt;   &lt;div id="right"&gt;     &lt;a href="#" class="related-article third" align="middle"&gt;       &lt;img src="fossil.turtle2.jpg" alt="Turtle"&gt;       &lt;h3&gt;Uncovering the world's greatest mysteries&lt;/h3&gt;     &lt;/a&gt;   &lt;/div&gt; &lt;/div&gt;     All help would be gladly appreciated.
How can I horizontally center a &lt;div&gt; within another &lt;div&gt; using CSS? &lt;div id=&quot;outer&quot;&gt;   &lt;div id=&quot;inner&quot;&gt;Foo foo&lt;/div&gt; &lt;/div&gt;
"1 in 10 are" or "1 in 10 is"? Take the examples:   "One in ten children are dyslexic."  "One in ten children is dyslexic." "One in ten children has dyslexia." "One in ten children have dyslexia."   The "one" is singular so 2 and 3 should be correct. But the "one in ten" is a fraction" so 1 and 4 should be correct. And yet I think I usually say 1 and 3. Which is/are correct?! Getting disk i/o statistics for single process in Linux Adding parentheses around subfig references Say I have a figure with two subfloats inserted using the subfig package.  When I reference them with \ref{myLabel} I get this     Figure 3.5a and 3.5b.     But what I want is this:     Figure 3.5(a) and 3.5(b).   How can I add the parentheses? How do you keep user.config settings across different assembly versions in .net? Jawa asked me this  and I didn't know the answer. So I present it to the meta SO community:     [To get the Yearling badge] Do you need to earn the 200 rep within that one year or is it enough to get 200 at some point after being a member for a year? And does 'a year' mean the very first 12 months or the last (sliding window of) 12 months?    I would assume that if you hit 200 reputation after you've already been around for a year, then you would get the Yearling badge. But I don't know. I was just wondering whether or not there have been mistakes in mathematics. Not a conjecture that ended up being false, but a theorem which had a proof that was accepted for a nontrivial amount of time before someone found a hole in the argument. Does this happen anymore now that we have computers? I imagine not. But it seems totally possible that this could have happened back in the Enlightenment.   Feel free to interpret this how you wish! permission denied BASH Use of 'const' for function parameters How far do you go with const?  Do you just make functions const when necessary or do you go the whole hog and use it everywhere?  For example, imagine a simple mutator that takes a single boolean parameter:  void SetValue(const bool b) { my_val_ = b; }   Is that const actually useful?  Personally I opt to use it extensively, including parameters, but in this case I wonder if it's worthwhile?  I was also surprised to learn that you can omit const from parameters in a function declaration but can include it in the function definition, e.g.:  .h file  void func(int n, long l);   .cpp file  void func(const int n, const long l)   Is there a reason for this? It seems a little unusual to me. How do I determine if my integrated Intel graphics support "Shader Model 3"? I am trying to play a Steam game on Ubuntu.  The game requires "Graphics: Shader model 3".  How do I determine if my integrated Intel graphics support Shader Model 3?  At present, when I launch the game, I hear the audio, but the screen is entirely black.  Running glxinfo | grep OpenGL yields:  OpenGL vendor string: Intel Open Source Technology Center OpenGL renderer string: Mesa DRI Intel(R) Haswell Mobile  OpenGL core profile version string: 4.5 (Core Profile) Mesa 18.2.2 OpenGL core profile shading language version string: 4.50 OpenGL core profile context flags: (none) OpenGL core profile profile mask: core profile OpenGL core profile extensions: OpenGL version string: 3.0 Mesa 18.2.2 OpenGL shading language version string: 1.30 OpenGL context flags: (none) OpenGL extensions: OpenGL ES profile version string: OpenGL ES 3.1 Mesa 18.2.2 OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.10 OpenGL ES profile extensions:   I am not sure which (if any) of the above lines answer my question. Is there a tool to get the lines in one file that are not in another? If $a_{ij}=\max(i,j)$, calculate the determinant of $A$ If $A$ is an $n \times n$ real matrix and       $$a_{ij}=\max(i,j)$$       for $i,j = 1,2,\dots,n$, calculate the determinant of $A$.   So, we know that   $$A=\begin{pmatrix} 1 &amp; 2 &amp; 3 &amp; \dots &amp; n\\  2 &amp; 2 &amp; 3 &amp; \dots &amp; n\\  3 &amp; 3 &amp; 3 &amp; \dots &amp; n\\  \vdots &amp; \vdots &amp; \vdots &amp; \ddots  &amp; \vdots\\   n&amp; n &amp; n &amp; \dots &amp; n \end{pmatrix}$$  but what do I do after? Unused Business visa I got a 6 months business visa for the UK. But I can't use it.   My relative lives in the USA. In the future, I want to go there to meet with her.  Is there any problem getting a US visa after getting, but not using, a UK business visa? Best way to clone an installation (copying to identical hardware) Kind-of like  but slightly different (I think), in that I have 6 identical Acer Aspire Revo R3610 machines. One is (almost) configured to my requirements - when I'm done preparing it I'd like to make the other 5 machines absolutely the same. I'm very new to Ubuntu, what's the most straightforward (easiest) way of doing this?  The machines are going to live on different networks if that might otherwise be a problem (eg with Windows you can clone disks but you then have to make registry changes afterwards if they're going to run on the same network etc). The hardware in all 6 machines is, I stress, the same!  How can I efficiently clone one source image on to these identical machines?  Please restrict one software/solution per answer How to prove there are no more positive integers that are products of 2 and 3 consecutive numbers? $6$ and $210$ share the property that both are the products of both two and three consecutive numbers. $6$ is $2\times3$ and $1\times2\times3$ and $210$ is $14\times15$ and $5\times6\times7$. It was easy enough to write a program to search for more numbers with this property, I found that there were no more up to at least $1{,}000{,}000{,}000{,}000$ ($1$ Trillion). But it is beyond me to prove that there are either no more numbers like this or to find the next one. Any ideas? Help, I cannot get my test code coverage higher than 75%! Code below Create bootable CD from ISO How and why do accelerating charges radiate electromagnetic radiation? Let's consider it case by case:  Case 1: Charged particle is at rest. It has an electric field around it. No problem. That is its property.  Case 2: Charged particle started moving (it's accelerating). We were told that it starts radiating EM radiation. Why? What happened to it? What made it do this?  Follow up question: Suppose a charged particle is placed in uniform electric field. It accelerates because of electric force it experiences. Then work done by the electric field should not be equal to change in its kinetic energy, right? It should be equal to change in K.E + energy it has radiated in the form of EM Waves. But then, why don't we take energy radiated into consideration when solving problems? (I'm tutoring grade 12 students. I never encountered a problem in which energy radiated is considered.) How do you photograph rain? What are recommended settings for my Nikon Coolpix P1 to best portray rain?  Here's what I got. No retouching was applied.   The picture I took when the rain was heavy with the automatic settings:  The picture I took with the "Sports" program; by then, however, the rain was not as hard. Ugh, ugly gray strip at the bottom, that was the flat surface I put my camera on to get a stable picture.   My main problem is that the actual rain and hailstorm is very hard to see in the picture. The overall effect is, instead, of fog.    Follow-up from the thread, courtesy of more rain, now with less hailstorm and more thunder.  The feedback amounted to flash and faster shutter. I took a few photos and I'm having some trouble to reconstruct what I did to get each result. Two representative results:   Fast shutter, with some guest starring:I'm talking about that horrible building obviously. Faster shutter and flash:Kinda difficult to say those pictures were taken sixty seconds of each other. :)   I'm not sure, however, that either of this is really an improvement of the original results. This problem is from a practice exam I was working on.     What is the cardinality of the quotient $\mathbb{Z}[x]/(x^2-3,2x+4)$ ?   Thoughts. If I find a ring that is easier to handle then this then I can go from there. So I think this is isomorphic to $\mathbb{Z}_2[x]/(x^2-3,x+2)$. And then I am stuck.  Am I correct so far? What should I be looking to do from here?  Thanks for your time and your answers. lcm versus phi in RSA In textbook RSA, the Euler $\varphi$ function $$\varphi(pq) = (p-1)(q-1)$$ is used to define the private exponent $d$. On the other hand, real-world cryptographic specifications require the Carmichael lcm function $$\lambda(pq) = \operatorname{lcm}(p-1,q-1)$$ to define $d´$. It is clear that the $d´$ divides $d$, and therefore using $d´$ may be more efficient than using $d$. My question is: Are there any further reasons, e.g. regarding security, why one should not use $d$?