## Mathcast #4: Quick squaring of 2-digit numbers

Here's a video on how to quickly square a 2-digit number. The technique is based on this algebra:

If you have a number with digits "ab" then the number is 10a+b.

(10a+b)^2 = 100a^2+20ab+b^2.

If you enjoy this video check out all of the Wild About Math! mathcasts.

[youtube]http://www.youtube.com/watch?v=_wjxgz6r-_U[/youtube]

## Mathcast #2: Quick multiplication of two 2-digit numbers

I've produced a second mathcast, this one using Camtasia screen recorder. I've posted the mathcast on You Tube and you can watch it right here without leaving the blog. This video shows you how to quickly multiply together a pair of two digit numbers without having to write down the intermediate results.

[youtube]http://youtube.com/watch?v=0pkVARKaG6U[/youtube]

This is the second in a series of videos I'll be producing on arithmetic tips and tricks.

The first mathcast was here. It was about very quick multiplication for special cases of numbers.

If you enjoy this video check out all of the Wild About Math! mathcasts.

Check back frequently for new videos and for interesting Math-related articles, especially ones with fun activities. Tell your friends and subscribe to the RSS feed or email list to stay current on Wild About Math! happenings.

Enjoy.

## The first ever Wild About Math! mathcast

Ever since starting this blog a couple of months ago I have felt that text and graphics could only go so far in helping people to get wild about Math. I knew that video was the next step in helping to explain mathematical ideas and in getting more people engaged in Math. But, until a few days ago I didn't know what it would take to produce a Math video.

Well, as luck would have it, some searching on the net led me to a fellow Math lover, Tim Fahlberg (Tim.Fahlberg@mathcasts.org), who just happens to have tons of experience producing mathcasts, which are broadcasts (videos) aimed at teaching Math. Tim, his Math professor sister Dr. Linda Fahlberg-Stojanovska, colleagues and students have produced tons of mathcasts. Tim, in fact, is a pioneer in producing mathcasts and I'm sure there will be many more of them produced in the future, especially as the needed technology gets better, cheaper, and easier to use.

Tim's business-related Wiki is here and his Math247 Wiki, with lots of mathcasts plus instructions on producing them, is here. I'll be writing more about Tim and what he's doing in future posts as there's tons to write about Tim and mathcasts. For now go ahead and check out his web-site and Wiki.

The very first mathcast is about how to quickly multiply together two-digit numbers if they meet two conditions. Check out the video. (Flash is required to watch the video.)

[voicethread b=26603]

This video is pretty primitive but I think it works. There's an error in one of the Math problems. See if you can find it. And, error aside, tell me if you find this video helpful, if you'd like to see more of them, and what subjects you'd like to see videos about.

I've got plans for more impressive productions but what's interesting about this video is how little technology it took to produce. While I was learning all about screen capture using Camtasia, and researching Whiteboard software and graphics tablets for producing mathcasts, Tim urged me to check out something I had never heard of, a free service called voicethread. Voicethread allows you to take one or more pictures, a slide show, and apparently some kinds of videos, and annotate them with voice, text, and by drawing on the screen. And, you can allow people to comment on your voicethreads with voice, text, and handwritten annotations ; Don't worry your original isn't damaged.

The neat thing about Voicethread is that its pretty easy to learn and use. I made this mathcast with my Windows XP laptop, an image file of the Math problems that I created with a whiteboard program called NotateIt, and an inexpensive microphone. Tim got me excited about the idea of encouraging kids to comment on mathcasts and to make their own. Voicethread does have some weirdnesses but once you get over them it's quite easy to produce fun videos quickly.

So, kids (and adults), do comment on the video. And tell your friends to check it out. Also, do tell me what kinds of Math problems and explorations you'd like covered in a video as I plan to make lots more, and more impressive looking ones as soon as I gather up everything I need and get some experience. But, don't ask me to show you how to do that Math problem that's due tomorrow. I can't be that responsive!

p.s. to fellow WordPress bloggers. Embedding videos in your blog can be a real pain as I'm sure many of you have discovered. The way to go is to find plug-ins that know about your particular video service and generate the proper HTML for you. Well, there's a plug-in for Voicethread. It's here. I discovered it at this blog article: Getting Voicethread and WordPress to play nicely.

If you enjoy this video check out all of the Wild About Math! mathcasts.