Natural Blogarithms

The four numbers A, B, A+B and A-B are all prime.  The sum of these four numbers is
A) EvenB) Divisible by 3C) Divisible by 5D) Divisible by 7E) Prime
Source: 2002 AMC 10/12B #15

I was having a problem when using Camtasia Studio to do a screen capture of an algebra lecture.  On my laptop, the capture works just fine but on my desktop it was very jumpy.  For those who don’t know, I use a Wacom Tablet, Microsoft OneNote and Camtasia to produce a series of videos [...]

I love these kinds of puzzles because there is only one solution but there are several ways to get there.  It’s at least as interesting to hear the different approaches as it is to solve it.
Here was the puzzle posted last week:
Mr. Jones has eight children of different ages.  On a family trip his [...]

An awesome new feature was recently announced by Google for the contact management tools in Gmail.  If you have multiple contact entries for the same individual in Gmail you can now easily merge them into one.

(From Lifehacker)
For example, if you’re staring in the face of numerous duplicate contacts that should represent the same person, [...]

   Mr. Jones has eight children of different ages.  On a family trip his oldest child, who is 9, spots a license plate with 4-digit number in which each of two digits appears two times. 
  “Look, daddy!” she exclaims. “That number is evenly divisible by the age of each of us kids!”
  “That’s [...]

Two days ago, I posted this simple little number puzzle. Quite a few folks came up with the answer below.  One of the interesting questions you can ask is whether that solution is unique.
 
Clearly there are two lines of symmetry in the original problem so by reflection alone we come up with a total [...]

I’m not keeping very good track of how many of these kind of puzzles I’m posting, so we’ll just say this is the 6th.
Problem: Place the digits 1 through 8 in the circles below such that no two adjacent circles contain consecutive digits.

 
Update: I was missing a couple of lines.  The picture is now [...]

Be careful what you say.  You MUST assume EVERYONE is listening.
Every semester, I try to remember to convey this idea to my students in each of my classes.  Those that use online social networking tools like Facebook, MySpace, LinkedIn, Twitter, etc., must assume that when they put themselves out there, no matter where it [...]