Monday, May 24, 2010

Martin Gardner - The Original 'Riddler'

Today and over the next few days, you will find, in the media and on many math and science blogs, many touching, almost reverential, tributes to the greatest puzzler of our generation. How I looked eagerly to the next edition of Scientific American when I was younger. We didn't have much money but my dad insisted on purchasing a subscription to this classic magazine, intended for those scientists and non-scientists who wanted to know what was happening in the forefront of modern science and mathematics. Of course, I turned immediately to the back page to tackle another set of Mr. Gardner's challenging puzzles. I was so proud of myself if I could solve even one of these! Many of his puzzles had an almost magical quality to them. Now you see it -- now you don't. My forte was the logic type of puzzle but I tried them all.

Martin Gardner died Saturday, 5-22-10, at the age of 95. (See the puzzle  created below in dedication to Mr. Gardner).
By the way, 95 = 19x5, 94 = 47x2, 93 = 31x3.
It is only fitting that he left us at an age which is the largest 2-digit number with exactly two prime factors.

For you puzzlers out there, here is my conundrum dedicated to Mr. Gardner. Feel free to submit your solution, but only one,  in the comments to this post. Our readers can choose which one they think is the most elegant. I found one way, but I'm certain there are others!

Can you form 95 using each of the digits 5-2-2-1-0 exactly once. No restrictions on the arithmetic operations, parentheses, factorials, roots, logs, etc...  You may combine the digits to form numerals like 12 or 120.

He was not a mathematician, nor a professor, nor a scientist. Yet I feel strongly that he deeply influenced all of these groups as well as anyone who enjoyed the satisfaction of challenging the mind. Read about him in the Wikipedia article and in the many tributes. If you're too young to have experienced the sheer joy brought to so many of us then discover it for yourself by looking at the annals of Scientific American or reading one of Mr. Gardner's many books.

Martin Gardner was more than a maker of puzzles of course. He was also known as a debunker of quackery and pseudoscience. He was an amateur magician, a philosopher, a lover of knowledge, a true Renaissance Man - a man for the ages.

Dr. Gardner - thank you for making a difference in my life and the life of so many others. Now if only I could remember how to get the cherry out of the martini glass by moving two matches...

On behalf of all my fellow bloggers, my sincerest condolences to your family.


"All Truth passes through Three Stages: First, it is Ridiculed... Second, it is Violently Opposed... Third, it is Accepted as being Self-Evident." - Arthur Schopenhauer (1778-1860) You've got to be taught To hate and fear, You've got to be taught From year to year, It's got to be drummed In your dear little ear You've got to be carefully taught. --from South Pacific


robotguy said...

I always loved Gardner's stuff, but keep getting him mixed up with A.K. Dewdney.

I'm guessing we shouldn't submit answers to your riddle in the comments?

Dave Marain said...

Henry Dudeney preceded Gardner and was probably the supreme puzzlemaster of the late 19th century. He and Gardner were simply the best!

I suspect there are are several solutions to the "95" puzzle so go right ahead and submit in the comments, but just submit one solution. If we get a few, then our readers can vote on the most elegant one or simply appreciate the creativity!

Mr. Lomas said...

I came up with several - I will choose this one since the digits are in order...

5! - (2+2)! - 1 - 0

Dave Marain said...

Mr L --
Yup, that's the one i found and I like it for the reason you stated. If no one responds with any other methods by Tue AM, please offer another one of your solutions!

robotguy said...

I was just about to hit "publish" when I realized I used 0 twice (10^2-5+2*0). Whoops, I guess I'll have to keep looking...

On another note, I had never heard of Dudeney. I'll have to check him out. I was thinking of this guy:

robotguy said...

Aha! You even mention in your post that 95=19*5:

Dave Marain said...

I knew you'd see that one!!

Here's a solution which exploits the fact that 0! = 1:

(2^5)(2+1) - 0!

I thought we might find 3 solutions, but now I suspect there are others.

I do like these kinds of activities for prealgebra students but, allowing more advanced mathematical functions and operations, might make it interesting for the upper level student as well. What is it about these kinds of puzzles that seem to engage people...

I never heard of Dewdney so thanks for making me aware.

Nate Perez said...


Nate Perez said...


jd2718 said...


Jan said...

Has seriously no-one suggested the 120-25 variant? :)

Eric Jablow said...

The floor symbols aren't done well in this font on my Mac. I hope they show up better for most people:

⌊201/2⌋ - 5 = ⌊100.5⌋ - 5 = 100 - 5 = 95.