Sunday Times Teaser 2788 – Red-Letter Days
by Nick MacKinnon
Published: 28 February 2016 (link)
The months of my 2016 calendar are headed M, T, W, Th, F, Sa, Su, with the dates 1, 2, 3 … in a grid of squares underneath. I have shaded all the days on which I have meetings planned — all of them being on weekdays. For example, in February the days 1, 2, 3, 4, 8 and 9 are shaded: these shaded squares form a connected piece and the product of the numbers is a perfect cube. The same is true of the shaded squares in another month — and in fact it’s the largest possible such cube in the calendar. My last meeting in that month is on my aunt’s birthday.
What is her birthday?