Sunday, February 22, 2009

Mathematical Chuck Norris Facts

For the unfamiliar, there is a class of jokes about how awesome Chuck Norris is. Here I will post those with mathematical twist.

• Chuck Norris counted to infinity, twice.
[www.chucknorrisfacts.com, as of 2009-02-22]

• Chuck Norris knows the last digit of pi.
[www.chucknorrisfacts.com/page8.html, as of 2009-02-22]

• Chuck Norris can divide by zero.
[www.chucknorrisfacts.com/page2.html, as of 2009-02-22]

• If you have five dollars and Chuck Norris has five dollars, Chuck Norris has more money than you.
[www.chucknorrisfacts.com, as of 2009-02-22]

• The square-root of -1 is not imaginary. It's just hiding from Chuck Norris.
[Ben, 2009-02-22]

• The shortest distance between two points is Chuck Norris.
[org.]

• The square root of 2 is rational number for Chuck Norris.
[org.]

• Chuck Norris can square the circle, double the cube and trisect an angle using only his fingers for a compass and his arm for a straight edge.
[org.]

Saturday, February 21, 2009

Subtraction Without Borrowing

clipped from www.youtube.com

Subtraction Without Borrowing by MathVentures [Video Prototype 01]

This is my first video prototype. Lots of room for improvement,

Clay Shirky: Institutions vs. collaboration

clipped from www.youtube.com

Clay Shirky: Institutions vs. collaboration

Monday, February 9, 2009

Testing Probability

Flummoxed by his true-false final exam, a student decides to toss a coin up in the air. Heads means true; tails, false. Thirty minutes later, he is done, well before the rest of the class. But then the student startsd flipping the coin again. And soon he's swearing and sweating over each question.

"What's wrong?" asks the concern teacher.

"I'm rechecking my answers," says the student.

[Comic Wendell Potter, Laugh!:), Reader Digest, March 2009, p. 81]

Uri's Comment: It is interesting to note that the student can change any answer that is not confirmed without affecting the probable grade of the test. Of course, for this to be true, the number of questions should be as large as possible. Considering that (a) it took the students 30 min. to finish the test and (b) it takes under 6 seconds to toss a coin and jot down the result, the test could have consisted of 150-300 questions (no need to spend time on reading each question). This test consists of a sufficient number of questions for probability to determine the overall grade.