yes, !! is also a math symbol

Join the channel to get exclusive and early videos, original music, lecture videos, and more!    / @wrathofmath   🛍 Check out the coolest math clothes in the world: https://mathshion.com/ More Math Chats:    • Math Chats   We introduce the double factorial !!, also called the alternate factorial. This cute little bit of mathematical notation gives us a way to achieve an effect similar to the standard factorial but while skipping every other number. The double exclamation point will respect the parity of its number, and proceed accordingly. We'll see examples of the factorial and double factorial, and then discuss perfect matchings in graph theory to see an example of where the double factorial is the solution to a problem. #maths #graphtheory #mathematics Matchings in Graph Theory:    • Matchings, Perfect Matchings, Maximum Matc...   Graph Theory Course:    • Graph Theory   Textbooks I Like! Graph Theory: https://amzn.to/3JHQtZj Real Analysis: https://amzn.to/3CMdgjI Abstract Algebra: https://amzn.to/3IjoZaO Linear Algebra: https://amzn.to/43xAWEz Calculus: https://amzn.to/3PieD1M Proofs and Set Theory: https://amzn.to/367VBXP (available for free online) Statistics: https://amzn.to/4d5HbUQ Discrete Math: https://amzn.to/3qfhoUn Number Theory: https://amzn.to/3JqpOQd ★DONATE★ ◆ Support Wrath of Math on Patreon:   / wrathofmathlessons   ◆ Donate on PayPal: https://www.paypal.me/wrathofmath Follow Wrath of Math on... ● Instagram:   / wrathofmathedu   ● TikTok:   / wrathofmathedu   ● X: https://x.com/wrathofmathedu