Volume 8
, Issue 2


In Figure 1, there are four different surfaces: the sphere, the cylinder, the torus, and the Mobius strip. I expect you are familiar with the first two of these.

Once again we are presenting a game for you to play (and maybe to analyze).


  1. Each digit is larger than the one before it and only one of them is odd.

Judging from the lack of responses to the "Sums of Squares" last time, most readers must have had some trouble with it.

This question seems to be creating some interest among our readers.

Find two positive integers $x,y$ so that $xy = x+y$

The sum of the numbers in a corridor (A Table of Corridors and Squares, Vol 8 No 1) can be represented as follows

"Thinking Machines" by Irving Adler

J181 Show that the product of 4 consecutive integers is always one less than a perfect square.

J171 Prove that for $n>2$,
$$(n!)^2 > n^n.$$