Double Factorials

This math video tutorial provides a basic introduction into double factorials and contrasts it with single factorials and iterated factorials.

Probability - Basic Intro:

Binomial Theorem:

Permutations and Combinations:

Factorials Explained!

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Parametric Equations:

Ellipses - Conic Sections:

Hyperbolas - Conic Sections:

Parabolas - Conic Sections:

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Arithmetic Sequences:

Geometric Sequences:

The Fibonacci Sequence:

Mathematical Induction:

Induction Divisibility:

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Final Exams and Video Playlists:

[abbeyrhapsody]

I didn't know there was a thing called "double factorial" so far! Thanks so much! You deserve more and more!

[vqgvvgw]

I graduated already, but feel I've learned a bit better under my personal studies(Math). No deadlines or pressures, thank you.

[nickoemmanuelvillacruz]

Never learned this in elem and high school

[Zersara]

Never knew single factorials existed!! School never teach us but this is really interesting ~ thank you for teaching us 💗

[georgesadler]

MR. Organic Chemistry Tutor, thank you for a great video on Double Factorials.

[_Just_Another_Guy]

I never learned about Double Factorials or Iterative Factorials in elementary or highschool either but these topics seem like it can be taught as early as junior year of highschool.

The concepts aren't that difficult to grasp. I was already being taught introductory calculus in junior year which is way more complex than Double Factorials and Iterative Factorials.

[dougdavis]

What is the functional use of a double factorial? Is there a triple factorial? A septuple factorial?

[coolmanchu]

Can you please make a video on graphing calculators?

[LanoMusambazi-srmx]

Thank you sir. I didn't know this double and iterated factorial.

[StevenTorrey]

When in practical math would a double or integrated factorial crop up? Or for that matter any factorial?

[nosir]

God blessed Earth with your happening and graciousness

[irichardoteng]

thanks for teaching me about this :)
this vid helped me alot with my upcoming test

[ვვვ]

(googolplex!)! Is it comperable with graham's number?

[reinlepiku]

All my calculators (CAS and non CAS) give different answers than in this video.
For example 3! = 720
The TI-86 and HP Prime can also calculate the double factorial of a number expressed as a decimal fraction. For example 3.3!! = 262289.062411
Also GOOGLE CALCULATOR on PC desktop can do it.
(Ti-89, TI-Nspire CX CAS cannot do this!)

[VisayasRealMe_]

Using odd and even numbers in double factorials

[jeemonjose]

Any reason why the double factorial is that specific way? Like you multiply every alternate number. And similarly, is a triple factorial something you get when you multiply every third number?

[olawunistephen]

Thank you so I need your help....for a video on LENS MAKER FORMULA... calculations and explanations ...pls

[tirthankarsingh]

Thanks a lot
This is something new I never saw .👍👍👍👍👍👍✌️✌️✌️✌️

[NeelTigers]

Students: Hmm..how can there be two factorials?
Legends: wait..why’s this dude so excited about 5

[dimuthupraboda]

Thank you. Love from srilanka.

I want to know. when I type double Factorials in a cal. why I get a factorial's factorial.

ex :-

3!! -> 720

It's like :-

3!! :- 6! :- 720