Science is built up of facts, as a house is built
   of stones; but an accumulation of facts is no
   more a science than a heap of stones is a house.

     —Henri Poincaré, French mathematician, 1908 more quotes

Simpson’s Paradox video, trigonometry,
many others

Alternate address for this page:


9/20/2016: This page, while still useful as a resource for links, is no longer being updated with new assignments. Please click here for the STA onCampus database.
. . . more


Shelby doubling as a mattress (2008)

This page is dedicated to the 40 passengers and crew members of United Airlines Flight 93. Additional information . . .

Students: Abbreviations are here.
Alumni: Please click here.

2015-16 classes: Click one of these

Algebra II





Blocks 2,3

Block 4

Block 6

Block 6 (fall only)


(Marriott Hall)


* Introduction to Programming Languages

** Mathematics of Digital Data




At other times, I am usually in my office. For more details, please see my contact information. To locate
other teachers, please check the teaching schedule, the extra help schedule, and the STA timetable.

Welcome to
Home Page and the Mathematics of Digital Data

General Information:
How to contact Mr. Hansen
Mr. Hansen’s three rules
Policies concerning absences
Information about Woody (my ancient dog, who died in July 2002)
Information about Shelby, a.k.a. the Shelbeast, who died in July 2015)
How to decipher those abbreviations you see on your papers

Fun Links:
The eyeballing game: educational, fun, and dangerously habit-forming (you have been warned!)
Prime numbers: Researchers have found new patterns!
Article on Benford’s Law, an amazing number pattern most people have never heard of
Mathcross puzzles for extra credit (and more Mathcross puzzles)
Elephant’s Wheels puzzles official contest information
Old version of Microsoft Excel contained arithmetic bugs
RSA-576, a $10,000 puzzle, has been solved! Click here for details (prizes up to $200,000)
The Poincaré conjecture has been solved! (The winner declined the $1 million prize. Mathematicians are sometimes a little odd.)
This article on the Poincaré conjecture ends by saying, “. . . a really good problem can sometimes be much better than a really good answer.”
Something special about many of the positive integers from 1 to 9999
Spinning dancer optical illusion
Some real-life optical illusions
Extraordinary optical illusions from MIT (Cambridge, MA) and the San Francisco Exploratorium
More from MIT: Graduate student pranksters use a phony research paper generator in an astonishing AI breakthrough
Zooming from 10 million light years away, down to the level of quarks—very, very cool
Angle-arc puzzles created by the Class of 2006 (in 2003) and the Class of 2007 (in 2004)
The best TV commercial ever! An article describes how the ad was shot in 606 takes—all real except for one second of digital animation.
Jim Loy’s math pages: a huge collection of mathematical facts, mostly recreational
Mathematical art (“polynomiography”)
Mind-reading program (Can you figure out the mathematical principle that makes this work?)
Interview with Bill Gates: how he wrote the operating system for the antique computers Mr. Hansen collects
How to interface the HP iPAQ 2210 with a vintage laptop computer
Overconfidence in the world of investment and elsewhere
Russian vocabulary drill, version 1.00.00 as of 3/25/2001 (requires Excel 97)
Russian keyboard driver for Windows 95/98
Two-column proof that girls are evil (Internet lint; author unknown)
Color test (harder than it looks—but fairly easy on the second try)
Mathematics for code-making and code-breaking at the National Cryptologic Museum
Someone other than a dead politician finally appears on currency!
Rules for depicting computers in movies [courtesy of the nonprofit Washington Apple Pi, Ltd.]
The barometer fable
A mathematical scavenger hunt
MP3 files (legal!)
Mr. Hansen’s blog (

Serious Links:
STA School Handbook
WolframAlpha, an advanced “computational knowledge engine” for mathematics and quantitative analysis
Mr. Hansen’s blog ( (I listed it a second time because it is both fun and serious.)
A Course in Number Theory for High School Students by David C. Garlock, who taught this course here at STA in May 2003
Errata page for the math/physics tome The Road to Reality by Sir Roger Penrose (published by Knopf, 2005)
Philosophy of St. Albans School: 1999 version  2010 version
New Orleans flooding as predicted in a 2002 newspaper series, more than 3 years before Katrina
Careers in mathematics
Summer camps for high school mathematics students
Global Children’s Organization: volunteer opportunities for students 17 and older
“The Real Heroes are Dead”: an amazing profile of Rick Rescorla from The New Yorker, 2002 (warning: rough language)
   . . . which serves as a segue to . . .

Page Dedication:

“. . . [O]nly one thing worked right in the nation’s defense. According to the final report of the 9/11 commission, it wasn't the FBI, CIA, FAA or Air Force. Not the National Security Council or the Department of Defense. Not the State Department or Border Patrol. . . . Only a small band of civilians, strangers to one another . . . managed to figure out what was going on in time . . . Brave passengers aboard United Airlines Flight 93 forced hijackers to crash the plane into an empty field far short of its target.”

— David Von Drehle, Washington Post staff writer, page A1, July 23, 2004

Lest we forget, that target was in the center of our city, most likely the U.S. Capitol. A temporary memorial near Shanksville, Pennsylvania, paid tribute to the passengers and crew of Flight 93, to whom we owe an inestimable debt of gratitude. The temporary memorial has since been replaced by a permanent memorial, which was dedicated on 9/10/2011, the day before the tenth anniversary of 9/11.


Pages from Previous Years:
-- STAtistics: 1998-99  1999-2000  2000-01  2001-02  2002-03  2003-04  2004-05  2005-06  2006-07  2007-08  2008-09  2009-10  2010-11  2011-12  2012-13  2013-14  2014-15
-- HappyCal (Honors AP Calculus BC):
1998-99  1999-2000  2000-01  2002-03  2006-07  2007-08  2008-09  2009-10  2010-11  2011-12  2012-13  2013-14
-- The Calculus (AP Calculus AB):
2003-04  2004-05  2005-06
-- IntroCal (Introduction to the Calculus):
-- Algebra II:
1998-99  1999-2000  2005-06
-- Geometry:
2000-01  2001-02  2002-03  2003-04  2004-05  2007-08  2008-09  2009-10
-- IPL (Introduction to Programming Languages): Spring 2011  Spring 2012  Spring 2014
-- AP Computer Science A/Java: 2012-13  2014-15
-- CFCS (Coding for Cybersecurity): Fall 2015
-- MODD (Mathematics of Digital Data): Spring 2004  Fall 2005  Fall 2006  Fall 2010  Fall 2011  Fall 2012  Fall 2013
-- Practical Statistics: Spring 2012
-- The Saint Albans News, for which I was faculty advisor May 1999–May 2004
-- June 1999 Commencement



My odometer on 11/20/2003 (199,999.9 miles)

Final result, June 2006:
246,582.7 miles

Old Blue has reached the end of the road—R.I.P.


Return to Mathematics Department home page

Return to St. Albans home page

Last updated: 20 Sep 2016