Today's Puzzle
Thursday, January 21
When I do laundry in the evening, I leave the light on in the laundry room so I'll remember to move the clothes to the dryer and to hang and fold them when they're done.
This system has some flaws in a multi-person household. My wife would turn off the light, thinking she had turned it on—or she'd leave it on, thinking I had turned it on when I hadn't. Communication is hard!
But my wife loves making systems, so she hung a card by the light switch that I could flip over to signal that the light was lit on purpose. She labeled the sides of this card in a non-straightforward (yet curiously logical) manner, using two rubber stamps from my voluminous collection. Which two, and which means what?
Hint
No. 5 isn't one of them. That's just bait.
Yesterday's Puzzle + Solution
What data are represented in this dotplot? Each dot represents a single occurrence, and the dataset is complete (to date).
BONUS: Identify the people associated with the smallest and largest values (which are 31 and 4452).
Solution
There were a few ways to figure this out. The spikes are at 1500 and 2900 days, which work out to about 4 and 8 years... and if you count the dots, there are 45 of them. These are the lengths of time former U. S. Presidents were in office. Maybe you can guess what was on my mind yesterday.
The shortest- and longest-serving Presidents were William Henry Harrison and FDR.
Credit for the concept of this puzzle goes to Robert Hayden.
Congratulations to yesterday's solvers Jason, Kate, Dr. Yetman, Mr. Gregg, and Hazel. Go Team Grown-Ups! Thanks to everybody who made a guess!
About This Site
Though he now teaches mathematics, Dr. (né Mr.) Shapiro's first job in a K–12 school was as a lunch monitor in Davis, CA. It was there that he originated the Puzzle of the Day, even rewarding correct answers with tickets in denominations like "15 points" (though without a clear idea of how he'd ultimately redeem these). Dr. Shapiro's favorite puzzle from this pre-professional era was "Tell me the location of the beehive on this campus."
Ten years later, Dr. Shapiro revived Puzzle of the Day at Proof School, writing each day's puzzle on a name tag. After 600 puzzles or so, he was just starting to feel normal about students reading his chest all the time when campus closed and the puzzle, like the rest of our lives, moved online. New puzzles are posted daily on school days.
Want to catch up on old PotDs? There's an archive currently containing puzzles from March to December 2020.