Math Forum / Mathematics / Recreational Math / December 2007

Recently I found a triangle center related to the Conway circle :
http://www.geocities.com/avni_math/
Comments and discussions are welcome.
Best regards,

Hi again.  Thinking about the game rolling 10 sided dice, where 8 9 or 10
is a success and any 10 is rerolled with any additional 8 9 or 10's added, I
was trying to think of a way to quickly calculate odds.
Obviously adding up possible rolls in my head for, say, 6 dice, isn't

This problem was inspired by the site
http://www.crescentofbetrayal.com/proof.htm ,
which makes the claim that a memorial to be built near Shanksville in
southwestern Pennsylvania, where Flight 93 crashed on

could anybody here tell me how to solve the following difference
equation
(1)    f(t) = a/2 ( f(a(t+1)) + f(a(t-1)) )
where a>0. The function should be "reasonable", i.e. bounded and

Going back to a previous thread from September ... a couple of you were
working out the probability of a particular word being drawn from a bag of
100 tiles. The word used as an example was MINIMAL. P(MINIMAL) was
calculated as follows...

I play a certain game that used 10 sided dice.  The other day someone
needed 3 successes and got it with his 7 die.  Now, in this game an 8, 9 or
10 is counted as a success.  If you roll a 10, you get to roll again, and if
you get another 8, 9 or 10 it's another success, with ...

For those that like to sit back and read a more "light-hearted"
article about math than the occasional academic paper, I found these
articles on wikihow.com to be very interesting and very fun at the
same time:

when i was a wee little tyke in college
i used to doodle strange sieves on a page
 while the professor would blather on about polyandry in tibet
 or fortran loops

The following problem is quite surely well-known but I couldn't
find anything about it in the web.
Let a_0 = 2 and let's define a_(i+1) by
a_(i+1) = min{ k | 1/a_0 + 1/a_1 + ... + 1/a_i + 1/k < 1 }.

The other night, I went to an author's presentation in a local library
by Gerald R. Rising about his new book "Inside Your Calculator:
From Simple Programs to Significant Insights".
It is in the same genre as the best math book I have ever

Can anyone help me prove that f(x) = ln(1+x^2)-e^(-x) +1 is increasing in R?
Thanks

In describing a coronal mass ejection that occurred on
1 September 1859, author Stuart Clark in "The Sun Kings"
writes (page 172):
  Traveling more slowly than the light and X-rays,