Online Meeting of the Recreational Mathematics Group

Hi

You are invited to the meeting of the Recreational Mathematics Group, on Wednesday 30th March, at 7 pm. This meeting will be online using Zoom.

We will talk once more about the combinatorial problem of counting the regions into which n straight lines in general positions divide the plane. OEIS sequence A090338 at https://oeis.org/A090338 refers to this topic, and provides interesting references.

If we have time we might discuss the Hat-Check puzzle, now more usually known as the problem of Derangements: A cloakroom attendant completely loses track of which of n hats belong to which customers, and hands them back at random to their n customers as the latter leave. What is the probability that none of the customers receive their own hat?

Michael Sheeran