April 17, 2013 by mlaforge

105 – cто пять – cent cinq – ciento cinco

105 is a triangular number. Here are the first four triangular numbers. Get it? Can you figure out which triangular number 105 is? How did you decide?

In the year 105 AD Ts’ai Lun of China created paper from hemp, tree bark, rags and fishnets that quickly replaced silk and bamboo strips. Papermaking didn’t reach Europe until the 12th century.

105 only has 3 prime factors: 3, 5, and 7

The atomic number of hahnium, also known as dubnium is 105.

State Route 105 is a highway in the south-central part of the U.S. state of Maine. SR-105 begins in Augusta at Cony Circle where it junctions with U.S. Route 201 and continues east approximately 45 miles (72 km) until it terminates atU.S. 1 in Camden. It is regarded as one of the most scenic drives in Maine.

China National Highway 105 (G105) runs from Beijing to Zhuhai, via Langfang, Chuangzhou, Dezhou, Donge, Jining, Shuangyou, Fuyang, Liuan, Jiujiang, Nanchang, Ji’an and Guangzhou. It runs to approximately 2,717 km, and, on a map, runs broadly on a straight line from Beijing to Guangzhou. Through the Lotus Bridge it is connected to Macau.

Hot 105 FM is a popular radio station in Hollywood Florida

p. 105 of War and Peace begins “Prince Andrei was leaving the next evening.”

The other book I’m reading: The Extraordinary Advenures of Alfred Kropp, begins thus on p. 105: “The Sword has the power to heal as well as to rend.”

Just sayin’.

Best,

LaForge

References:

Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987): 134, via Wikipedia

http://www.puzzles.com/puzzlesineducation/handsonpuzzles/TriangularNumbers.htm

My copies of War and Peace (the new translation) and Alfred Kropp

April 15, 2013 by mlaforge

Euler’s Birthday

It is Leonard Euler’s birthday today. The Google doodle above is animated, a little bit, so if you click it, above, I have linked to the doodle. Here’s what Time had to say…

Click to get the entire article, which includes this provocative paragraph…

Provocative WHY? Because there was a poll in 1988?!?! And I missed it? Well, okay, I was 19, but still…

AWESOME. Just saying. Here is a link to another mathematical blogger. He is very engaging and has some excellent puzzles on his site: The Math Less Travelled

Best wishes to you all, and with sympathy for those affected by the Boston tragedy today,

M. LaForge

Image April 7, 2013 by mlaforge

Coolest Library Ever! SO much to count and read.

I love counting things. This library is SOOO appealing for this, among other, reasons. Cincinnati Public Library 1974. Click to see the WHOLE picture from Retronaut.com

April 6, 2013 by mlaforge

Thinking about Units and, well…cake.

A quick recap. I asked a group of people what 8+9 was and a few brave souls said 17. Some more reticent folks chimed in with loud nods and “mmmhmmm”‘s. Still others held their peace. When asked “How do you know?”, I received 5 answers:

I had it memorized.
I doubled 8 and added 1.
I doubled 9 and subtracted 1.
I was teaching base 10 the other day and so I thought 1-ten and seven 1’s.
Not enough information. I need units.

This last from a self (and university) proclaimed engineer who noted that if the 8 is 8 inches and the 9 is nine feet then you’ll be adding 8 inches to 108 inches for a total of 116 inches. He is a friend and colleague so I gently mocked him, but on not much further reflection, I had to admit that it was a great answer.

Then I was thinking about how I promised to post my Flourless Chocolate Cake recipe, for M&S if for no one else and I was looking for my pan so I could show the pan that the cake goes in..

.<first pan picture…the BanPan because this is how I found it>

and I started wondering about the volume of the cake. If I ate the whole cake by myself, would I have eaten the equivalent of…what? What would be meaningful…the bottles of iced tea I drink? Four apples? How many chickpeas? And this is pure volume, not calories or anything like that. But then I got distracted again, because the next picture I took of the pan looked like this:

Oooh. Look at the cool shape the light made. So–of course–I imported it into Grapher which is a program for Macs that I believe is free and it is AWESOME. It will show you the pictures that go with the stories that the equations were created to tell or to describe. And then I made a line, a leftward facing parabola and a circle so that together they would make that shape carved out by the light. Here it is! First with the coordinate grid and then without. And I darkened the lines and made them turquoise. (Love Grapher.)

And then I thought that maybe you would like to see the equations, in case you wanted to do something like this yourself. I KNOW they look complicated, but it really just three shapes, told to not go too far.

OK, so MAYBE I’ll get back to volume some time. Next post. But I do have other things to share with you.

TWITTER did right by me this weeks. Check these out:

And this leads you to the “It’s OK to be smart” website and from there to a site which reports newly published papers on physics…

One more from JH that leads you to an unusual artist, featured at the blog…

and here is a picture of the fog, sculpted. Click the picture to read more about this artist’s process:

Don’t you want to see them? Here’s one. Click to get more.

Click to see it!

This one too!

I think I’ll end there. I have articles on Girls in Stem, including an article written by 17 year old Catherine Wong about Science in High School. But my brain is feeling pretty happy right now and I think I’ll go listen to an audiobook while I clean up. I really wish someone would make an audio version of Dianne Wynne Jones’ Fire and Hemlock, but today I’ll be happy with Laurie R. King’s Garment of Shadows, a Sherlock Holmes and Mary Russell mystery.

I’ll leave you with one last (funny) picture of my Flourless Chocolate Cake pan, and the recipe. I hope you can read it. Oh, and a at the top is a picture of my youngest daughter with a camera made out of cans. Because who doesn’t want to see that?