## Mathematics and Multimedia Carnival #4

Welcome to the fourth edition of the Mathematics and Multimedia Blog Carnival.

* Note: All images in this post are from Wikipedia.

The Number 4

- Four is the smallest composite number, its proper divisors being 1 and 2. Four is also a highly composite number. The next highly composite number is 6.
- Four is the second square number, the second centered triangular number.
- 4 is the smallest squared prime (p
^{2}) and the only even number in this form. It has an aliquot sum of 3 which is itself prime. The aliquot sequence of 4 has 4 members (4, 3, 1, 0) and is accordingly the first member of the 3-aliquot tree.

The Entries

(1) Jacqueline Barbour presents Teach addition so your child can remember it posted at Pain Free Math. A nice approach to using very simple props and a number line to teach addition and subtraction.

(2) Milo Gardner presents Ahmes Papyrus, New and Old Classifications posted at New and Old Ahmes Papyrus classifications,. The history of Western mathematics includes 200 rational number based problems recorded in Egyptian (2050 BCE to 1550BCE) unit fractions. The RMP is sometimes called Ahmes' Papyrus, named after its scribe. The hieratic text described 87 problems: 20 arithmetic, 10 algebraic, 10 geometric, 46 economic (weights and measures) and one mod 7 recreational problem known in the medieval era as "Going to St. Ives". Forms of unit fraction arithmetic remained in use until 1454 AD, the latest text was Fibonacci's Liber Abaci, Latin writing Europe's arithmetic book from 1202 AD to 1454 AD, and fully replaced by base 10 decimals by 1585 AD.

(3) Ed Pegg Jr presents Happy Vampire Day posted at Wolfram Blog. "October has a rather special day—10/05/2010 is a vampire date, since 10052010 = 5001 × 2010. The next two 8-digit vampire dates are 10/05/2064 and 10/19/2248. As a puzzle, try to figure out how to rearrange their digits into two 4-digit numbers, which have a product of the original number."

(4) zar presents Dimostrazione senza parole (demonstration without words) posted at Gli studenti di oggi. Zar's blog is written in Italian, but this particular post is "without words."

(5) Erlina Ronda presents GeoGebra and Mathematics: Investigating coordinates posted at Keeping Math Simple.

(6) John Golden presents Fraction Multiplication posted at Math Hombre -- A Geogebra visualization for multiplying fractions, along with a novice screencast and a discussion of embedding geogebra in a blog.

(7) William Emeny presents A sequences alternative to ‘how many matchsticks’ posted at Great Maths Teaching Ideas. "Make lessons on sequences much more interesting by adding context! Use sequences to analyse skyscrapers!"

(8) David Wees presents The Death of the Amateur Mathematician posted at Professional blog | 21st Century Educator. This is a discussion about what is happening in the field of education today.

(9) John Cook presents Variations on factorial! — The Endeavour posted at The Endeavour.

(10) Rebecca Zook presents How To Multiply Binomials Using a Box! posted at Triangle Suitcase - Rebecca Zook's Blog About Learning. "Many people find this "box" method for multiplying binomials more intuitive than foiling. I created this series of short videos to share this idea with other math teachers and students."

(11) Guillermo Bautista presents Mathematics in Microsoft Office « Mathematics and Multimedia posted at Mathematics and Multimedia. This is an article on integrating mathematics to office suites.

(12) Last but not least, I submit my own review of The Mystery of the Prime Numbers. This is an amazing book, with great illustrations that looks like a children's book but will appeal to anyone who wants to dive deep into simple ideas.

This concludes our third Carnival of Mathematics and Multimedia. The next Carnival will be hosted at the Math Hombre blog on November 8th. Submit your entries here.

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Guillermo BautistaOctober 11th, 2010 - 16:58

Excellent format. Thank you for hosting. You are welcome to host again next year.

Rebecca ZookOctober 17th, 2010 - 15:24

Hey Sol, I’m so glad to be included! Yay for number four!! Great job with all the fun images – they make me smile. Thank you for putting this together – I’m looking forward to investigating everyone’s entries!

I saw in your bio that you like to help people touch math. Do you know about the Math U See curriculum? They have some really cool manipulatives. And I saw that you help people do math together in real time using interactive tools over the internet. Me, too! What tools are you using these days?