## Archive for May, 2010

### RIP Martin

May 23, 2010

Martin Gardner passed away yesterday (May 22) at the age of 95 — a number that is 0 mod 1, 1 mod 2, 2 mod 3, and 3 mod 4, as I’m sure he’d appreciate.    It seems like half the puzzles I hear about were either invented by him or popularized by him.  Falling into the latter category are the flexagons, which are, of course, a favorite of Godzilla and which were described in the first “Mathematical Games” column of Scientific American (you know, according to Wikipedia).

A quick search reveals lots of puzzles, most of which have a visual component.  As a treat, here’s a quick one that doesn’t (from the group Gathering for Gardner):

• Write out the alphabet starting at J (and ending at I):
JKLMNOPQRSTUVWXYZABCDEFGHI

Now erase all the letters that have vertical symmetry, like M.

There will be 5 groups of consecutive letters left.  Write the number of letters in each group:

___   ___   ___   ___   ___

Cool, huh?

Scientific American itself just posted 3 Gardner puzzles here in tribute to the man who served them well for many years.

Martin, thanks for the fun.

### A billion here, a billion there; soon you’re talking a real portfolio!

May 6, 2010

What is a billion?

• In contemporary USA, it is 109
• In contemporary France, it is 1012
• In the UK prior to the early 1970s, it is 1012
• In the UK after the early 1970s, it is 109
• In most European countries, it is 1012
• In 19th C France, it is 109
• In 14th – 18th C France, it is 1012
• It is a modernized spelling of “bymillion”, a word introduced in 1475 by Jehan Adam for a million2. (He also coined the term “trimillion” for a million3, and similar vocabulary for higher powers, vestiges of which remain in our number systems.)

Apparently, a billion is also a wickedly large number of shares of stock to be trading at one time. For if you accidentally hit the “b” key instead of the “m” key at your computer, and thus execute a trade in billions of shares instead of millions of shares, you might cause the Dow Jones Industrial Average to drop 9 percent in a matter of moments on a Thursday afternoon. Or so I’ve heard.