Volume 18
, Issue 3


Perhaps the first law of motion should say "what goes up and comes down must have stopped to turn round".

In my previous article about geometrical transformations I have described two methods, namely parallel translation and similarity transformation.

The art of writing secret messages, intelligible to those who are in possession of the key and unintelligible to all others, has been studied for centuries.

Some interesting applications of calculus appeared in the 1981 3 unit and 4 unit papers. Firstly two geometrical extreme value problems:

Q.539 From the set of whole numbers $\left\{ 0,1,2,\ldots , 999999999\right\}$ two are selected at random. What is the probability that they differ by a multiple of 10000?

Q.515 I have two different integers  $> 1$. I inform Sam and Pam of this fact and I tell Sam the sum of my two numbers and I tell Pam their product. The following dialogue then occurs: