867-5309; more than Jenny’s phone number

A few days ago I posted a video about the twin prime conjecture, which states that there are infinitely many primes that are two integers apart: 3 and 5, 5 and 7, 11 and 13, 101 and 103, 1607 and 1609… Well, check this out. Type 8675309 into WolframAlpha and it says: “Jenny’s phone number.”…

Applets for multivariable calculus

When I was in Portland a few weeks ago for MathFest 2009 I attended the minicourse Creating Demonstrations and Guided Explorations for Multivariable Calculus using CalcPlot3D by Paul Seeburger. Paul has created some applets to be used in calculus classes (mostly, but not exclusively, multivariable calculus). They can be found on his Exploring Multivariable Calculus…