Duane Habecker<p>A puzzle for students of all ages.
<a class="hashtag" href="https://bsky.app/search?q=%23RecreationalMath" rel="nofollow noopener noreferrer" target="_blank">#RecreationalMath</a> <a class="hashtag" href="https://bsky.app/search?q=%23iTeachMath" rel="nofollow noopener noreferrer" target="_blank">#iTeachMath</a> <a class="hashtag" href="https://bsky.app/search?q=%23MathSky" rel="nofollow noopener noreferrer" target="_blank">#MathSky</a> </p>
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#mathsky
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dhabecker<p>A puzzle for students of all ages.</p><p><a href="https://mathstodon.xyz/tags/RecreationalMath" class="mention hashtag" rel="tag">#<span>RecreationalMath</span></a> <a href="https://mathstodon.xyz/tags/iTeachMath" class="mention hashtag" rel="tag">#<span>iTeachMath</span></a> <a href="https://mathstodon.xyz/tags/MathSky" class="mention hashtag" rel="tag">#<span>MathSky</span></a></p>
Andrew J. Steinmetz<p>What's your Erdős number? Mine is 5. 🧮 <a class="hashtag" href="https://bsky.app/search?q=%23AcademicSky" rel="nofollow noopener noreferrer" target="_blank">#AcademicSky</a> <a class="hashtag" href="https://bsky.app/search?q=%23MathSky" rel="nofollow noopener noreferrer" target="_blank">#MathSky</a> <a class="hashtag" href="https://bsky.app/search?q=%23Math" rel="nofollow noopener noreferrer" target="_blank">#Math</a>
<a href="https://mathscinet.ams.org/mathscinet/freetools/collab-dist?source=1443426&target=189017" rel="nofollow noopener noreferrer" target="_blank">mathscinet.ams.org/mathscinet/f...</a><br><br><a href="https://mathscinet.ams.org/mathscinet/freetools/collab-dist?source=1443426&target=189017" rel="nofollow noopener noreferrer" target="_blank">MathSciNet</a></p>
Karen Campe<p>New blog post! "Mental Math Monday" summarizing last week's question and many different calculation strategies.<br /><a href="https://mathstodon.xyz/tags/MTBoS" class="mention hashtag" rel="tag">#<span>MTBoS</span></a> <a href="https://mathstodon.xyz/tags/iTeachMath" class="mention hashtag" rel="tag">#<span>iTeachMath</span></a> <a href="https://mathstodon.xyz/tags/T3Learns" class="mention hashtag" rel="tag">#<span>T3Learns</span></a> <a href="https://mathstodon.xyz/tags/MathChat" class="mention hashtag" rel="tag">#<span>MathChat</span></a> <a href="https://mathstodon.xyz/tags/MentalMathMonday" class="mention hashtag" rel="tag">#<span>MentalMathMonday</span></a> <a href="https://mathstodon.xyz/tags/MathStratChat" class="mention hashtag" rel="tag">#<span>MathStratChat</span></a> <a href="https://mathstodon.xyz/tags/ElemMathChat" class="mention hashtag" rel="tag">#<span>ElemMathChat</span></a> <a href="https://mathstodon.xyz/tags/MathSky" class="mention hashtag" rel="tag">#<span>MathSky</span></a> <a href="https://mathstodon.xyz/tags/MathsToday" class="mention hashtag" rel="tag">#<span>MathsToday</span></a> <a href="https://mathstodon.xyz/tags/ClassroomMath" class="mention hashtag" rel="tag">#<span>ClassroomMath</span></a> </p><p>Thanks to Howie Hua!!!</p><p><a href="https://karendcampe.wordpress.com/2025/04/07/mental-math-monday/" target="_blank" rel="nofollow noopener noreferrer" translate="no"><span class="invisible">https://</span><span class="ellipsis">karendcampe.wordpress.com/2025</span><span class="invisible">/04/07/mental-math-monday/</span></a></p>
Andrew J. Steinmetz<p>Oh, I'm excited to read this! <a class="hashtag" href="https://bsky.app/search?q=%23MathSky" rel="nofollow noopener noreferrer" target="_blank">#MathSky</a> 🧮<br><br>RE: <a href="https://bsky.app/profile/did:plc:nogtf77xcyjilq52agusqrjx/post/3lm7ezxvf4s25" rel="nofollow noopener noreferrer" target="_blank">https://bsky.app/profile/did:plc:nogtf77xcyjilq52agusqrjx/post/3lm7ezxvf4s25</a></p>
mrahikka<p><a href="https://mathstodon.xyz/tags/math" class="mention hashtag" rel="tag">#<span>math</span></a> <a href="https://mathstodon.xyz/tags/mathsky" class="mention hashtag" rel="tag">#<span>mathsky</span></a></p><p><a href="http://mikkorahikka.blog/2025/03/20/pyoristysvirheista-pythonissa-ja-geogebrassa/" target="_blank" rel="nofollow noopener noreferrer" translate="no"><span class="invisible">http://</span><span class="ellipsis">mikkorahikka.blog/2025/03/20/p</span><span class="invisible">yoristysvirheista-pythonissa-ja-geogebrassa/</span></a></p>
mrahikka<p><a href="https://mastodontti.fi/tags/math" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>math</span></a> <a href="https://mastodontti.fi/tags/mathsky" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>mathsky</span></a></p><p><a href="http://mikkorahikka.blog/2025/03/20/pyoristysvirheista-pythonissa-ja-geogebrassa/" rel="nofollow noopener noreferrer" translate="no" target="_blank"><span class="invisible">http://</span><span class="ellipsis">mikkorahikka.blog/2025/03/20/p</span><span class="invisible">yoristysvirheista-pythonissa-ja-geogebrassa/</span></a></p>
ajsteinmetz<p>The totally antisymmetric Levi-Civita tensor ε^(αβγδ) has two conventions:<br>(A) ε^(0123) = +1<br>(B) ε_(0123) = +1</p><p>The physics textbooks Schwartz, Peskin & Schroeder, Itzykson & Zuber, and Jackson use (A) while Bjorken & Drell, and Wald use (B). Quite annoying! <a href="https://beta.argyle.social/tags/Science" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Science</span></a> <a href="https://beta.argyle.social/tags/Physics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Physics</span></a> <a href="https://beta.argyle.social/tags/MathSky" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathSky</span></a> 🧪⚛️🧮</p>
Maths Mastermind<p>Maths Mastermind - Day 80</p><p>BOOST YOUR BRAIN POWER WITH THIS FUN <a href="https://mastodon.social/tags/MATHEMATICS" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MATHEMATICS</span></a> <a href="https://mastodon.social/tags/PUZZLE" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>PUZZLE</span></a> !!! </p><p><a href="https://mastodon.social/tags/Math" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Math</span></a> <a href="https://mastodon.social/tags/Riddle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Riddle</span></a> <a href="https://mastodon.social/tags/MathSky" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathSky</span></a> <a href="https://mastodon.social/tags/MathsRiddle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathsRiddle</span></a> <a href="https://mastodon.social/tags/MathsPuzzle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathsPuzzle</span></a> <a href="https://mastodon.social/tags/MathPuzzle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathPuzzle</span></a> <a href="https://mastodon.social/tags/Puzzles" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Puzzles</span></a> <a href="https://mastodon.social/tags/MentalHealth" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MentalHealth</span></a> <a href="https://mastodon.social/tags/MathRiddles" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathRiddles</span></a></p>
Maths Mastermind<p>Maths Mastermind - Day 79</p><p>BOOST YOUR BRAIN POWER WITH THIS FUN <a href="https://mastodon.social/tags/MATHEMATICS" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MATHEMATICS</span></a> <a href="https://mastodon.social/tags/PUZZLE" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>PUZZLE</span></a> !!! </p><p><a href="https://mastodon.social/tags/Math" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Math</span></a> <a href="https://mastodon.social/tags/Riddle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Riddle</span></a> <a href="https://mastodon.social/tags/MathSky" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathSky</span></a> <a href="https://mastodon.social/tags/MathsRiddle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathsRiddle</span></a> <a href="https://mastodon.social/tags/MathsPuzzle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathsPuzzle</span></a> <a href="https://mastodon.social/tags/MathPuzzle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathPuzzle</span></a> <a href="https://mastodon.social/tags/Puzzles" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Puzzles</span></a> <a href="https://mastodon.social/tags/MentalHealth" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MentalHealth</span></a> <a href="https://mastodon.social/tags/MathRiddles" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathRiddles</span></a></p>
mrahikka<p><a href="https://mastodontti.fi/tags/math" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>math</span></a> <a href="https://mastodontti.fi/tags/geometry" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>geometry</span></a> <a href="https://mastodontti.fi/tags/mathsky" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>mathsky</span></a></p><p><a href="http://mikkorahikka.blog/2025/03/08/tim-brzezinskin-mieleton-kolmio/" rel="nofollow noopener noreferrer" translate="no" target="_blank"><span class="invisible">http://</span><span class="ellipsis">mikkorahikka.blog/2025/03/08/t</span><span class="invisible">im-brzezinskin-mieleton-kolmio/</span></a></p>
mrahikka<p><a href="https://mathstodon.xyz/tags/math" class="mention hashtag" rel="tag">#<span>math</span></a> <a href="https://mathstodon.xyz/tags/geometry" class="mention hashtag" rel="tag">#<span>geometry</span></a> <a href="https://mathstodon.xyz/tags/mathsky" class="mention hashtag" rel="tag">#<span>mathsky</span></a></p><p><a href="http://mikkorahikka.blog/2025/03/08/tim-brzezinskin-mieleton-kolmio/" target="_blank" rel="nofollow noopener noreferrer" translate="no"><span class="invisible">http://</span><span class="ellipsis">mikkorahikka.blog/2025/03/08/t</span><span class="invisible">im-brzezinskin-mieleton-kolmio/</span></a></p>
Maths Mastermind<p>Maths Mastermind - Day 78</p><p>BOOST YOUR BRAIN POWER WITH THIS FUN <a href="https://mastodon.social/tags/MATHEMATICS" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MATHEMATICS</span></a> <a href="https://mastodon.social/tags/PUZZLE" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>PUZZLE</span></a> !!! </p><p><a href="https://mastodon.social/tags/Math" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Math</span></a> <a href="https://mastodon.social/tags/Riddle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Riddle</span></a> <a href="https://mastodon.social/tags/MathSky" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathSky</span></a> <a href="https://mastodon.social/tags/MathsRiddle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathsRiddle</span></a> <a href="https://mastodon.social/tags/MathsPuzzle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathsPuzzle</span></a> <a href="https://mastodon.social/tags/MathPuzzle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathPuzzle</span></a> <a href="https://mastodon.social/tags/Puzzles" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Puzzles</span></a> <a href="https://mastodon.social/tags/MentalHealth" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MentalHealth</span></a> <a href="https://mastodon.social/tags/MathRiddles" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathRiddles</span></a></p>
Maths Mastermind<p>Maths Mastermind - Day 77</p><p>BOOST YOUR BRAIN POWER WITH THIS FUN <a href="https://mastodon.social/tags/MATHEMATICS" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MATHEMATICS</span></a> <a href="https://mastodon.social/tags/PUZZLE" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>PUZZLE</span></a> !!! </p><p><a href="https://mastodon.social/tags/Math" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Math</span></a> <a href="https://mastodon.social/tags/Riddle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Riddle</span></a> <a href="https://mastodon.social/tags/MathSky" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathSky</span></a> <a href="https://mastodon.social/tags/MathsRiddle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathsRiddle</span></a> <a href="https://mastodon.social/tags/MathsPuzzle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathsPuzzle</span></a> <a href="https://mastodon.social/tags/MathPuzzle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathPuzzle</span></a> <a href="https://mastodon.social/tags/Puzzles" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Puzzles</span></a> <a href="https://mastodon.social/tags/MentalHealth" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MentalHealth</span></a> <a href="https://mastodon.social/tags/MathRiddles" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathRiddles</span></a></p>
Andrew J. Steinmetz<p>The totally antisymmetric Levi-Civita tensor ε^(αβγδ) has two conventions:
(A) ε^(0123) = +1
(B) ε_(0123) = +1
The physics textbooks Schwartz, Peskin & Schroeder, Itzykson & Zuber, and Jackson use (A) while Bjorken & Drell, and Wald use (B). Quite annoying! <a class="hashtag" href="https://bsky.app/search?q=%23Science" rel="nofollow noopener noreferrer" target="_blank">#Science</a> <a class="hashtag" href="https://bsky.app/search?q=%23Physics" rel="nofollow noopener noreferrer" target="_blank">#Physics</a> <a class="hashtag" href="https://bsky.app/search?q=%23MathSky" rel="nofollow noopener noreferrer" target="_blank">#MathSky</a> 🧪⚛️🧮</p>
Andrew J. Steinmetz<p>Fun little derivation of the relativistic energy-momentum relation from the free Dirac wave equation using a determinant. <a class="hashtag" href="https://bsky.app/search?q=%23Science" rel="nofollow noopener noreferrer" target="_blank">#Science</a> <a class="hashtag" href="https://bsky.app/search?q=%23Physics" rel="nofollow noopener noreferrer" target="_blank">#Physics</a> <a class="hashtag" href="https://bsky.app/search?q=%23MathSky" rel="nofollow noopener noreferrer" target="_blank">#MathSky</a> 🧪⚛️🧮</p>
Maths Mastermind<p>Maths Mastermind - Day 76</p><p>BOOST YOUR BRAIN POWER WITH THIS FUN <a href="https://mastodon.social/tags/MATHEMATICS" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MATHEMATICS</span></a> <a href="https://mastodon.social/tags/PUZZLE" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>PUZZLE</span></a> !!! </p><p><a href="https://mastodon.social/tags/Math" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Math</span></a> <a href="https://mastodon.social/tags/Riddle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Riddle</span></a> <a href="https://mastodon.social/tags/MathSky" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathSky</span></a> <a href="https://mastodon.social/tags/MathsRiddle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathsRiddle</span></a> <a href="https://mastodon.social/tags/MathsPuzzle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathsPuzzle</span></a> <a href="https://mastodon.social/tags/MathPuzzle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathPuzzle</span></a> <a href="https://mastodon.social/tags/Puzzles" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Puzzles</span></a> <a href="https://mastodon.social/tags/MentalHealth" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MentalHealth</span></a> <a href="https://mastodon.social/tags/MathRiddles" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathRiddles</span></a></p>
Maths Mastermind<p>Maths Mastermind - Day 75</p><p>BOOST YOUR BRAIN POWER WITH THIS FUN <a href="https://mastodon.social/tags/MATHEMATICS" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MATHEMATICS</span></a> <a href="https://mastodon.social/tags/PUZZLE" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>PUZZLE</span></a> !!! </p><p><a href="https://mastodon.social/tags/Math" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Math</span></a> <a href="https://mastodon.social/tags/Riddle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Riddle</span></a> <a href="https://mastodon.social/tags/MathSky" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathSky</span></a> <a href="https://mastodon.social/tags/MathsRiddle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathsRiddle</span></a> <a href="https://mastodon.social/tags/MathsPuzzle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathsPuzzle</span></a> <a href="https://mastodon.social/tags/MathPuzzle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathPuzzle</span></a> <a href="https://mastodon.social/tags/Puzzles" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Puzzles</span></a> <a href="https://mastodon.social/tags/MentalHealth" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MentalHealth</span></a> <a href="https://mastodon.social/tags/MathRiddles" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathRiddles</span></a></p>
Maths Mastermind<p>Maths Mastermind - Day 74</p><p>BOOST YOUR BRAIN POWER WITH THIS FUN <a href="https://mastodon.social/tags/MATHEMATICS" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MATHEMATICS</span></a> <a href="https://mastodon.social/tags/PUZZLE" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>PUZZLE</span></a> !!! </p><p><a href="https://mastodon.social/tags/Math" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Math</span></a> <a href="https://mastodon.social/tags/Riddle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Riddle</span></a> <a href="https://mastodon.social/tags/MathSky" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathSky</span></a> <a href="https://mastodon.social/tags/MathsRiddle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathsRiddle</span></a> <a href="https://mastodon.social/tags/MathsPuzzle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathsPuzzle</span></a> <a href="https://mastodon.social/tags/MathPuzzle" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathPuzzle</span></a> <a href="https://mastodon.social/tags/Puzzles" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Puzzles</span></a> <a href="https://mastodon.social/tags/MentalHealth" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MentalHealth</span></a> <a href="https://mastodon.social/tags/MathRiddles" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathRiddles</span></a></p>
Andrew J. Steinmetz<p>The student said to the Master, "Sir, I do not understand the Dirac delta function." The Master then slapped the student across the face, and the student was enlightened. <a class="hashtag" href="https://bsky.app/search?q=%23Science" rel="nofollow noopener noreferrer" target="_blank">#Science</a> <a class="hashtag" href="https://bsky.app/search?q=%23Physics" rel="nofollow noopener noreferrer" target="_blank">#Physics</a> <a class="hashtag" href="https://bsky.app/search?q=%23MathSky" rel="nofollow noopener noreferrer" target="_blank">#MathSky</a> 🧪⚛️🧮 (shamelessly taken from elsewhere)</p>
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