Monthly Archives: March 2013

Divisibility by 17

Posted on March 30, 2013 by jrh794

I thought that a test for divisibility by 17 ought to work like the test for divisibility by 13 that I described in my last post.  No such luck.  But something similar does work. And here is a rough explanation why the method works.

Posted in Cool Ideas, Math Explorations | Tagged , , | Leave a comment

Divisibility Test for Thirteen

Posted on March 28, 2013 by jrh794

My department chair, Sherry Ettlich, sent us a link to this video which shows a quick (new?) method of determining if a number is divisible by 7. After I figured out how it worked, it occurred to me to try the same … Continue reading →

Posted in Cool Ideas, Math Explorations | Tagged , , | 1 Comment

Math Makes Me Happy

Posted on March 18, 2013 by jrh794

I wrote previously about how I love math and it makes me sad.  This article, Physics, Logic, Topology and Computation: A Rosetta Stone by John C. Baez and Mike Stay makes me very happy especially the table on page 66 and … Continue reading →

Posted in Cool Ideas, Math and Me | Leave a comment

What to Know About a Function

Posted on March 12, 2013 by jrh794

When I introduce the concept of function in my college algebra class, I emphasize that the formula is not enough.  To really know a function is to know its formula and its shape (graph) and its domain and range and … Continue reading →

Posted in Cool Ideas, Curriculum, Teaching, Uncategorized | Tagged , , , | Leave a comment

Completing the Square Versus The Quadratic Formula

Posted on March 9, 2013 by jrh794

My college algebra class is learning to find the zeros of polynomial functions, so we are solving lots of quadratic equations.  If the quadratic expression is not easily factorable, I have been saying. “Just use the Quadratic Formula.”  Here is … Continue reading →

Posted in Curriculum, Pedagogy, Teaching | 2 Comments