March 2012 - Page 9 of 10 - Math and Multimedia

Week in Review 1 – March 2012

March 4, 2012 GB High School Mathematics, Post Summary

Welcome to another edition of Week in Review. Looks like another busy week is ahead. I will be in Baguio for a 3-day training, so I am not sure if I’ll have the time to write there.

For a little bit of promotion, Baguio is the summer capital of the Philippines. The temperature there is relatively lower (15˚C to 26˚C, but can drop down to 7˚ C) compared to Metro Manila (23˚C-37˚C). It’s a great place to go if you want to escape summer heat.

Anyway, before my Baguio escapade, here are the list of post for this week.

Mathematics and Multimedia

My Other Blogs

Square Within a Square (applet) at GeoGebra Applet Central
Similarity and Architecture at Mathematical Palette
Mirrors and Symmetry at Mathematical Palette
Edraw Mind: A Vector-Based Mind Mapping Software at School of Freebies

Updated GeoGebra Tutorials (now in version 4.0)

Explore Math and Multimedia

That’s all for this week. Have a happy weekend everyone.

Leave a comment GeoGebra, GeoGebra Tutorial, math and multimedia, week in review

Divisibility by 8

March 3, 2012 GB High School Number Theory

This is the seventh post in the Divisibility Rules Series. In this post, we will discuss divisibility by 8.

A number is divisible by $8$ if the last three digits is divisible by $8$ . For example, $25816$ is divisible by $8$ since $816$ is divisible by 8. On the other hand, $5780$ is not divisible by $8$ since $780$ is not divisible by $8$ . Why is this so?

Let us start with $25 816$ . First, we know that $1000$ is divisible by $8$ . Therefore, $2000$ , $3000$ , $4000$ , and all multiples of $1000$ are divisible by $8$ . Since $25 816 = 25000 + 816$ and $25 000$ is divisible by $8$ , we just have examine the last three digits. Notice that this is similar to $5780$ . Since $5780 = 5000 + 780$ , and $5000$ is divisible by $8$ , we are sure that it is not divisible by $8$ since the last three digits is not divisible by $8$ .

This observation can be generalized because all numbers greater than $1000$ can be expressed as multiple of 1000 + three-digit number (the hundreds, tens, and ones). Since all multiples of $1000$ are divisible by $8$ , we just have to examine the divisibility of the last three digit number.

Of course this observation is also similar with negative numbers. All negative numbers less than $-1000$ can can be expressed as multiple of -1000 + three-digit negative number.

2 comments divisibility by 8, divisibility rules, divisibility test

3D Math Applets Galore at Maths.Net

March 2, 2012 GB High School Geometry, High School Mathematics

Last year, I have shared about an applet for visualizing isometric views. I found another superb 3d math applets site, Maths.Net, through Great Maths Teaching Ideas. Maths.net includes applets for exploring prisms, nets, platonic solids, and other 3-dimensional objects. It also includes an applet for building polyhedra.

My favorite applet is Guess the view. It lets guess the isometric view of a particular solid.

It turned out that the applets in Maths.Net are also from Wisweb, the same site where I discovered the isometric views applet.

5 comments 3d applets, 3d math applets, java applets

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