Find the radius.

Source: https://x.com/h0h0v/status/1700920145726607608?s=46&t=J5p2QDpKtxBQkQIPlkVWjg

#RecreationalMath

Trying to clear out my backlog of pentominoes puzzles that I haven't shared yet so I can create some sort of pentominoes bingo game for students to participate in throughout the year.

Up today:
Pentominoes Goose Puzzle
https://mathequalslove.net/goose-pentominoes-puzzle/

#mtbos #iteachmath #classroommath #classroomgames #pentominoes #recreationalmath #mathed

#RecreationalMath

I’m reading a wonderful book with my library app – Libby – when I discovered it provides data on my rate of reading.

How long will it take me read the book?

#RecreationalMath

Source: https://twitter.com/sonukg4india/status/1683038643655700481?s=46&t=J5p2QDpKtxBQkQIPlkVWjg

Happy SEVENS day (7-14! Or 14-7 for those who use DDMM) and here's my 2021 post celebrating Super Sevens!

(Recent updates include heptagon images from the amazing Hannah Murray @MurrayH83 using 21st century pattern blocks)

https://karendcampe.wordpress.com/2021/07/14/super-sevens/
#MTBoS #iTeachMath #MathEd #ClassroomMath
#RecreationalMath

A square has been cut into four rectangles with the given areas. What is the length of x?

#RecreationalMath
#iTeachMath

Source: https://twitter.com/h0h0v/status/1678073252092993539?s=46&t=J5p2QDpKtxBQkQIPlkVWjg

I've made a thing that helps you to make a printable template for a hexaflexagon, with your choice of pictures on each of the three faces: https://somethingorotherwhatever.com/hexaflexagon/

You can take a photo with your camera, or upload a file.

#hexaflexagon #math #RecreationalMath

#RecreationalMath
https://mathstodon.xyz/@benleis/110646135269642000

Find the blue area.
#RecreationalMath

Mathematical Date in a Year (Leap Year Version)

1/2 Permutation Day: "102 is the smallest number with three different digits" [NG]

1/6 Golden Ratio Day I

2/7 e Day

2/16 square and fourth power day

2/22 - twins and triplets day

3/11 - permutable prime day, the 71st day in a leap year, 311 and 71 are both permutable primes. [OEIS:A131687]

3/14 Pi Day

6/9 Rotational Symmetry Day; "205 days remain until the end of the year"[WP]

6/18 Golden Ratio Day II

6/28 Perfect Number Day

7/9 Double Prime day: 7 is a prime; 9 is a prime; 709 is a prime, 907 is a prime; 191st day in a leap year [OEIS:A131687]

7/14 Egyptian fraction day [OEIS:002966]

7/22 Pi Approximation Day

9/12 Programmer Day - 256th day in a leap year

10/1 Parity Day

10/21 Squarefree Day -- 295th day in a leap year. 10, 21, 295, 1021 are both squarefree numbers.

10/24 2^10 day

11/11 Single's Day

11/23 Fibonacci Day

12/21 Palindrome day

Reference:
https://en.wikipedia.org
https://www.engadget.com/amp/2016/01/01/the-complete-guide-to-geek-holidays/
https://blog.tanyakhovanova.com/2022/05/my-vision-for-number-gossip/
https://oeis.org/A131687
http://numbergossip.com/

#recreationalMath

Is anyone else into change ringing? I started playing around with swapping adjacent characters in a sequence, and started graphing the edges so it's easier to trace out and play the sequence on my ukulele. It struck me that this is a similar sort of thing to change ringing, though the paths I'm following through the graph don't enumerate all the sequences available
#recreationalmath #math #music

Fun #geometry problem from KH2020H0 on TW:
Find area of square given 4 equal semicircles w/diameter 10 cm.
#RecreationalMath

Spoiler in next post.

A nice problem.
Source: https://twitter.com/kh2020h0/status/1609538885352046594?s=46&t=Wa7VMSKtp3Q8vSqubujkQA

#RecreationalMath

A holiday present for those who like #RecreationalMath, specifically #RecreationalCombinatorics.

Today on the way to work, I happened to notice that there's a nice, combinatoric-style formula for the first n integers convolved with themselves (e.g., sum((1:4)*(4:1))=20).

Who can find the nicest, combinatoric-style explanation?

Ooh, ooh! Looks like there's only one order-3 #MagicSquare, so I had to try 4th-order. I finally got one by putting 7...10 in the middle:

14, 1, 15, 4
3, 8, 10, 13
6, 9, 7, 12
11, 16, 2, 5

Uh oh... this is fun!

#RecreationalMath #MathPuzzle #RecreationalMaths

Oh hey, I tried making a #MagicSquare with n=3, did I do it right? After about 10 tries, finally got the rows, cols, & diags sum to 15...

6 1 8
7 5 3
2 9 4

#RecreationalMath/#RecreationalMaths

Mentioned in passing in an old blog post I am finally reading (Playful Math Education, Blog Carnival #157 at http://mathmamawrites.blogspot.com/2022/07/math-teachers-at-play-aka-playful-math.html) is the observation that 157 is the 37th prime, and 37 is also prime.

Now 37 is the 12th prime, and 12 is not prime. That makes me sad but intrigued.

What is the longest chain of prime numbers of this sort? That is "N1 is the N2th prime, and N2 is the N3rd prime, and N3 is the N4th prime…" and so on?

#NumberTheory #RecreationalMath #OEIS ?

https://youtu.be/GWA_NraxOUw

#recreationalmath

#RecreationalMath #protip. 4k+1 numbers are _never_ prime over the complex integers. So if you encounter one, you can _always_ find a way to factor it.

For example, I saw 773 on a license plate the other day, and factored it as (22+17i)(22-17i).

You'll never be bored again.

This one is a very recent post from www.gogeometry.com (One of my favorite #geometry sites) Hopefully Antonio will setup an account here at some point. #mathpuzzle #recreationalmath