B R Sitaram Here are the answers to last month’s questions. Q 1. On WhatsApp, I got a message that March 2019 will be special, as for the first time in 560 years, there would be five Sundays in the month. Why should I dismiss this statement as hype? A. These statements come very often, with the first time in so many years, the only difference being in the number of years claimed! These statements are wrong when they state that such events are rare. In fact our calendar (the Gregorian one) is periodic. It repeats itself after 28 years, so the calendar for 2019 is the same as the calendar for 1991, 2047, 2075, etc. So any event connected with the Gregorian calendar has to repeat itself after 28 years! In fact, calendars can repeat after shorter time periods (6 years or 11 years), depending on the remainder you get when you divide the year by 4. For example, the calendar for 2019 will repeat in 2030 (after 11 years), again in 2036 (after 6 years) and again in 2047 (after 11 years). Q 2. How long is a day (in hours)? A. This is actually a tricky question. The word “day” is used in two different senses: the time when the sun is visible (day and night) and the duration from noon to noon. We use the second interpretation a lot. For example, the “day” in Monday, Tuesday, etc., the fact that we have 7 days in a week, 365 days in a year, etc. If I had intended the first meaning, the correct answer would have been, “varies from 0 hours to 6 months, depending on where you live.” If I had intended the second meaning, the correct answer would have been 24 hours! There are many similar words that we use in an ambiguous fashion: plant (think of plants, shrubs, grasses and trees vs. the plant kingdom), animal (are animals and nematodes different or are nematodes part of the animal kingdom?), man (as in man vs woman or as in ancient man), etc. Q 3. One of the persons referred to in Harry Potter and the Sorcerer’s Stone, who is credited with discovering the Sorcerer’s (or Philosopher’s) Stone is a historical figure. Who is he? A. The historical figure is Nicholas Flamel, who was a scribe during the 14th-15th Century. His name comes up repeatedly in the book. Two hundred years after his death, legends started appearing about his alchemy and