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David Joyner
Works at USNA
Attended Georgia Institute of Technology
Lives in arnold, md
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David Joyner

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Interesting chess position due to José Paluzie. Every square where the B king can be placed but the three illegal ones leads to mate in one!
#chess
#chessproblem
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wendy krieger's profile photoJDS Purohit's profile photoDavid Joyner's profile photo
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+JDS Purohit The black king can be placed anywhere legal and it's mate in one, yes.
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Clever proof that the elementary school math test question has no solution.
What happened next is a sad indictment of school maths
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Ondřej Čertík's profile photoTom Nathe's profile photoChristopher Smy's profile photoJason Bandlow's profile photo
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Not to detract from the central point, but that felt like too difficult of a "trick" to expect an 8yo to find.

I wonder if this was intended to be a "casting out nines" problem (check wikipedia if you haven't seen this). That can reasonably be taught to students that age and, if you know it, it's is easy to see the numbers given will always give 4 mod 9, and so 9000 is impossible.

I wonder if they had been taught this. (The fact that the student in question didn't seem to know it is not strong evidence, IMO)
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David Joyner

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Foes of Batman
The Gotham universe is complicated. This post is designed to help provide some order by listing the foes/adversaries of Batman, the DC Comics creation. Amygdala (Gotham City, Aaron Helzinger) Anarky (Gotham City, Sam Young) Anchoress (in Arkham Asylum). She...
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David Joyner

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This is depressing:-)
Here’s a chart to show you how long you have until you start to feel your age.
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Cool TSP vid
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Interesting article on math edu. Also there is this nice quote:

In the words of Michael Jordan: “I’ve missed 3,000 shots. Twenty-six times the game-winning shot has been trusted to me, and I’ve missed. I’ve lost over 300 games. I’ve failed over and over and over again, and that is why I’ve succeeded.”
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Amber Peall's profile photoDavid Joyner's profile photoDavid Foster's profile photoMichael Rector's profile photo
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+David Foster​ I never thought of math as an exercise. That is a great analogy. No one goes to a gym 3 times and says "well, I'm not stronger. Guess I'm not an exercise person." They keep at it and get better. That is how we need to look at math. The only thing we need is something to motivate people to work on their math exercises. Unfortunately doing math won't give you the body you want with 6pack abs which is a motivation for going to the gym. 
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Interesting Python podcast - this one is on Sagemath!
#python
#sagemath
#mathedu
Talk Python To Me is a podcast for developers who are passionate about Python. Learn about the language and related technologies.
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David Joyner

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Foes of Batman
The Gotham universe is complicated. This post is designed to help provide some order by listing the foes/adversaries of Batman, the DC Comics creation. Amygdala (Gotham City, Aaron Helzinger) Anarky (Gotham City, Sam Young) Anchoress (in Arkham Asylum). She...
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David Joyner

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Foes of Batman
The Gotham universe is complicated. This post is designed to help provide some order by listing the foes/adversaries of Batman, the DC Comics creation. Amygdala (Gotham City, Aaron Helzinger) Anarky (Gotham City, Sam Young) Anchoress (in Arkham Asylum). She...
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For those teaching probability: Terry Tao posted about visualizing r.v.s on his blog:
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DGA top 80 vs WGA top 101
The Directors Guild recently released a list of the top 80 films (by DGA members, as voted by fellow DGA members). Likewise, the Writers Guild has a list of top 101 screenplays . This post tries to compare them. The rank in the first column refers to the DG...
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David Joyner's profile photoEd S's profile photo
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Ed S
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They are all very good films, that's for sure! (Although there are one or two I haven't seen...)
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Pretty funny when you think about it.
Our brains fool us all the time. And we typically have no idea that it’s happening.
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Mind boggling, mind blowing stuff here. Very interesting. 
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Work
Occupation
math prof
Employment
  • USNA
    math prof, present
Places
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Currently
arnold, md
Previously
mountain view, ca - kent, wa - decatur, ga - princeton, nj - san diego, ca
Story
Tagline
math, writing, tech, edu, ...
Introduction
Enjoy tinkering with mathematics, writing, Sage (www.sagemath.org), video, chess, and photography. Interested in math education-related and open-source software issues.
Bragging rights
have managed to stay off facebook
Education
  • Georgia Institute of Technology
    math
  • University of Maryland, College Park
    math
Basic Information
Gender
Male
I have used All for the Pet for years and never once had rude service. The store doesn't even open until 9am and Lisa often comes in early to help out people who want to drop off their pet before going to work. I think she does a good job with my pets and her prices are reasonable.
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