In Matters for Debate, David Singmaster (DS) discusses some topics relating to the use and misuse of decimal points: the use of a full stop in writing times of the day, confusion between the decimal point and a dot used for multiplication, and writing amounts of money.

These designs were prompted by the “pursuit curves” of Mr. I. J. Good The first one consists of his six ‘hyperboloids’ and the second an equal number of ‘spearheads’ The former possesses what may be termed cyclical symmetry and the latter triple axial symmetry

There seems to be a technical improvement in these designs over those of Mr. Good’s insofar as the black areas at the centre of his triangular doodles are conspicuous by their absence over here.

Except for the circle, for which the true anomaly v is proportional to the time t, the position of a body in orbit about a central body at a given time is simplest to derive for a parabola. The classical determination of the time of flight on a parabolic trajectory is through the integration of the dynamic equations of motion. (See Appendix.)

I wanted to call this article, Counting permutations that contain a specified number of cycles of a given length but the Editor pointed out the problems this might cause the Production Editor - it simply wouldn't fit the running head. Hence the chosen title and the subject matter. There is a very well known result, nonetheless startling, about the relative frequency of derangements amongst the permutations of [r] = {1,2,3,… , r }.

The Report was prepared at the request of the Sub-committee on Instruction of the British National Committee for Mathematics. It formed the basis of the presentation of the United Kingdom point of view in a discussion on the topic at the International Congress of Mathematicians held in Moscow in August, 1966.