## Friday, June 30, 2017

### Math Teachers at Play #109 (a blog carnival)

Who is 109?     109 is a twin prime, twinned with 107.    (from numbergossip.com)

If 109 is written in Roman notation (CIX), then it becomes reflectable along the line it is written on.
The pipe organ at the Cathedral of Notre Dame in Paris has 109 stops.
When chilled below minus 109°F, CO2 becomes a solid, called dry ice.
109 equals the square root of 11881 or 118 - 8 - 1.
The only three-digit prime formed by concatenation of consecutive numbers. [Silva]
109 = 1*2+3*4+5*6+7*8+9. [Silva
The Sun is just over 109 times the diameter of the Earth. [Friedman]
(from https://primes.utm.edu/curios/page.php/109.html)

A Puzzle: Can you make 109 from four 4's? (I don't promise that it's possible...)

At age 109, Augusta Bunge became the youngest living great great great great grandmother. Is that mom to the fifth power?

Math Teachers at Play is a monthly blog carnival, hosted at a different blog each month. I was hoping to give you 109 math links this month, but life intervened (parenting...) long before I got through my storehouse of cool stuff. There are plenty of goodies here, but not as many as I'd hoped.

Books
There has been an explosion of super cool mathy books since I last hosted MTAP. Here are some I know about. I am embarrassed to admit that I haven't read most of them, and so I can't guarantee how cool they are. Let me know in the comments.

Animations

Puzzles & Games

Early Math

Geometry

Probability & Statistics

Writing in Math Class

Math and ...

On Teaching

Random Stuff

I have more but it's bedtime and June is ending. Would you like to see your favorite blog post in next month’s playful math blog carnival? Submissions are always open!

(Note: Edited on 7/1 to add a few forgotten links, and fix a few broken links.)

#### 7 comments:

1. So many interesting posts! Good thing I have a long weekend for browsing... Thank you for hosting. :-)

2. "A Puzzle: Can you make 109 from four 4's? (I don't promise that it's possible...)"

It didn't seem possible... but I found a way to do it. It can be done!

1. Congratulations, Sharon! (I verified her solution.)

The rules for this type of puzzle: use four 4's and no other digits, use any other math symbols you want.

3. Susan, never forget your inspiration and ability to inspire. Sincerely From Calvin in M, Michigan

1. Calvin, please email me! Then we can have a real conversation. You comment actually belongs on my new post. (You'll see.)

4. Im an old school Gen X/ Millenial cusp. I prefer a now 'outdated" mode of conversation of communication with people on phones. But I will email soon if you prefer. You just keep living and I hope blessed. P.S. Chlorine is the enemey to the nasal and occular passages, I agree now. From Calvin

5. Calvin, Email me once to give me your phone number, and I am happy to switch to phone.