…I turned 45 today, which is the square root of 2025!
After this year, it won’t happen again until 2116, when the lucky ones reach 46…. and the last time it happened was 1936, for those hitting 44.
Very mundane and pointless (error, miscellaneous and personal)…
I approve of this post.
Happy birthday!
Matt Parker was also born in 1980 and he anticipated this coincidence back in 2015 in a Numberphile video about his then-current-favorite number being 2025.
And 10 years of planning lead to his followup video posted a few days ago.
Thanks for giving him credit, as I should have done, because his video is where I learned it. I would never have made the connection on my own!
Before reading the thread I figured you’d turned 49. I know you’re too young for 64 or 81, and I thinkyou’re too old for 36.
Happy birthday!!! 
A month ago for me. Did you learn about this from Matt Parker, because I did? If you didn’t here’s the video with some other math facts about 45 and 2025
If I may sidetrack this discussion with an, I think, equally significant birthday factoid, I was born in 1961. That was the last year that could be turned upside down (rotated 90°) and remain unchanged. The previous year with that property was 1881 and the next will be 6009.
This makes me special.
Some more trivia:
Later this month 9/16/25 will be a Pythagorean Square date, and at least in the Gregorian calendar, it’s the only one possible. The next Pythagorean triple date will be 10/24/26, and that’s the last one this century.
But later in the month is something more exciting:
9/27/2025 (or 09272025) is a perfect square 3045^2
And there’s a bonus:
If like much of the Gregorian-using world, you use day/month/year, it’s also a perfect square
27092025 is 5205^2
There are only two more ‘square dates’ like this that can be rearranged in this century, 1-1-2036 and 2-2-2084 (01012036 and 02022084). After that, you’ll have to wait until 8-8-2649! And the next time after that will also be the next time that the month and day are different: 04-22-3025.
I’m about to have a prime birthday, though turning 61 doesn’t feel very ‘prime’ to me.
I was told that, in years that are a perfect square, if you say 90° it means 180°. Perhaps that’s not universal?
2002, 2112, 2552, 2692, 2882 and 2962 can all be turned upside down on a digital clock.
How awesome! I would never have even thought of something like this.
Happy Birthday.
2002 /= 5005
Correct, 2002 is not 5005. And when you turn 2002 upside down on a digital clock, you get 2002. When you turn 5005 upside down, you get 5005.
You guys are rotating them about different axes (I think that’s the plural of axis).
@Munch is doing this:
@74westy is doing this:
Show off.
(Either way, 6s and 9s don’t do mirror image, so the poster I was responding to was rotating, not reflecting.)
I think the second one can also be rotating about the axis going through it from left to right (like it’s rolling towards/away from you), but I’m going to be sick if I keep looking at these.
Very cool. Thank you for sharing your birthday trivia.
And happy birthday!
