Today, I learned about:

Exactly four years have gone since I last wrote about what a leap day is, 2016-02-29.

And here we are again, four years older, and maybe even wiser! I was thinking about the poor guy that was born on 1896-02-29. He celebrated his birthday on the correct date of the year only when there were eight candles on his birthday cake. How come? Well, as you know a leap year normally happens only once every four years, but when the century is on its first year, then it must also be evenly divided by 400, i.e. 1600, 2000, 2400 etc. But then, he knew that if he lived that long, he would still celebrate it on the correct day with 12, 16, 20, 24, … candles!

‘Can you use an hourglass’?

Finally, here comes the solution to the riddle posted back in 2019-12-31:

You start with two loaded hourglasses at the same time. After 7 min, when the small hourglass is done, you turn it over and restart it.

After 11 min, when the big hourglass is done, you leave it as it is. But now you turn over the small hourglass, which has had a second run of 4 min, and let it run for the third time until it stops.

Voilà, you have now accomplished the task!

That’s what I learned in school !

Ref.:

*: What did you learn in school today ?