## All posts in category **Uncategorized**

# It Could Be Worse…

*Posted by John Quintanilla on March 30, 2020*

https://meangreenmath.com/2020/03/30/it-could-be-worse/

# Cat Cubed

Source: https://www.facebook.com/CTYJohnsHopkins/photos/a.323810509981/10151128278824982/?type=3&theater

*Posted by John Quintanilla on March 13, 2020*

https://meangreenmath.com/2020/03/13/cat-cubed/

# 250,000 page views

I’m taking a break from my usual posts on mathematics and mathematics education to note a symbolic milestone: meangreenmath.com has had more than 250,000 total page views since its inception in June 2013. Many thanks to the followers of this blog, and I hope that you’ll continue to find this blog to be a useful resource to you.

**Twenty most viewed individual posts:**

- All I want to be is a high school teacher. Why do I have to take Real Analysis?
- Analog clocks
- Anatomy of a teenager’s brain
- Beautiful dance moves
- Finger trick for multiplying by 9
- Full lesson plan: magic squares
- Full lesson plan: Platonic solids
- Fun with dimensional analysis
- High-pointing a football?
- Importance of the base case in a proof by induction
- Infraction
- Math behind Super Mario
- My “history” of solving cubic, quartic and quintic equations
- Sometimes, violence is the answer
- Student misconceptions about PEMDAS
- Teaching the Chain Rule inductively
- Thoughts on silly viral math puzzles
- Valentine’s Day card
- Was there a Pi Day on 3/14/1592?
- Welch’s formula

**Twenty most viewed series:**

- 2048 and algebra
- Another poorly written word problem
- Area of a triangle and volume of common shapes
- Arithmetic and geometric series
- Calculators and complex numbers
- Common Core, subtraction, and the open number line
- Computing e to any power
- Different definitions of e
- Exponential growth and decay
- Fun lecture on geometric series
- Inverse Functions
- Langley’s Adventitious Angles
- My Mathematical Magic Show
- Predicate Logic and Popular Culture
- Reminding students about Taylor series
- Slightly incorrect ugly mathematical Christmas T-shirts
- Square roots and logarithms without a calculator
- Wason selection task
- What I learned from reading “Gamma: Exploring Euler’s Constant” by Julian Havil
- Why does and ?

**Twenty most viewed posts (guest presenters):**

- Engaging students: Classifying polygons
- Engaging students: Congruence
- Engaging students: Distinguishing between axioms, postulates, theorems, and corollaries
- Engaging students: Distinguishing between inductive and deductive reasoning
- Engaging students: Equation of a circle
- Engaging students: Factoring quadratic polynomials
- Engaging students: Finding the domain and range of a function
- Engaging students: Finding x- and y-intercepts
- Engaging students: Inverse Functions
- Engaging students: Laws of Exponents
- Engaging students: Pascal’s triangle
- Engaging students: Solving linear systems of equations by either substitution or graphing
- Engaging students: Solving linear systems of equations with matrices
- Engaging students: Solving one-step and two-step inequalities
- Engaging students: Solving quadratic equations
- Engaging students: Square roots
- Engaging students: Translation, rotation, and reflection of figures
- Engaging students: Using a truth table
- Engaging students: Using right-triangle trigonometry
- Engaging students: Verifying trigonometric identities

If I’m still here at that time, I’ll make a summary post like this again when this blog has over 500,000 page views.

*Posted by John Quintanilla on July 5, 2019*

https://meangreenmath.com/2019/07/05/250000-page-views/

# Another poorly written word problem (Part 11)

Another bonehead word problem. Notice the word “her”. While Usain Bolt holds the current 100-meter world record of 9.58 seconds, the women’s world record is currently 10.49 seconds.

Source: https://www.facebook.com/FloTrack/photos/a.432324889444/10156764197654445/?type=3&theater

*Posted by John Quintanilla on March 18, 2019*

https://meangreenmath.com/2019/03/18/another-poorly-written-word-problem-part-11/

# Trigonometry for the heavens

I enjoyed this article from the magazine *Physics Today* about the historical background behind three-dimensional spherical trigonometry: https://physicstoday.scitation.org/doi/10.1063/PT.3.3798

*Posted by John Quintanilla on January 21, 2019*

https://meangreenmath.com/2019/01/21/trigonometry-for-the-heavens/

# Codes and Ciphers Teaching Resources Website

Somehow I found this fun website with various teaching resources using different coding and decoding methods: http://www.cimt.org.uk/resources/codes/?fbclid=IwAR2yX_yDK0UAmLB2acIgbk15wJMy_QXFJSuKaQOj3q-SlrFkuuuxpsEXoyI

*Posted by John Quintanilla on January 18, 2019*

https://meangreenmath.com/2019/01/18/codes-and-ciphers-teaching-resources-website/

# Slightly Incorrect Ugly Mathematical Christmas T-Shirts: Part 3

Here’s another T-shirt that I found in my quest for the perfect ugly mathematical Christmas sweater: https://www.amazon.com/Fibonacci-Christmas-Tree-Holiday-Shirt/dp/B07KCF1F6D/

Unlike the shirt in my previous post, this one actually gets the first ten rows of Pascal’s triangle correct. So that’s a good thing.

There’s one small error: while the Fibonacci numbers can be found by adding along shallow diagonals of Pascal’s triangle, this really shouldn’t be called a “Fibonacci Christmas Tree.”

Oops.

*Posted by John Quintanilla on December 14, 2018*

https://meangreenmath.com/2018/12/14/slightly-incorrect-ugly-mathematical-christmas-t-shirts-part-3/

# The Professor vs. the NSA

I didn’t know this interesting bit of internet history:

“It’s July 1977,” Hellman tells the audience. “Whit and I are involved in a major fight with NSA over the data encryption standard.”

American law banned the unlicensed export of weapons. Makes sense: the government doesn’t want civilians wandering into Moscow with a trenchcoat full of fighter jet parts. The question is: Does this law apply to abstract mathematical ideas? By developing new approaches to cryptography, are Hellman, Diffie, and their collaborators de facto arms traffickers? If so, Hellman says, “then by publishing our papers in international journals, we are in some sense exporting plans for implements of war.”

“I think the penalty,” Hellman recalls, “was something like five years in jail.”

Full story: https://mathwithbaddrawings.com/2017/10/11/the-professor-vs-the-nsa/

*Posted by John Quintanilla on October 1, 2018*

https://meangreenmath.com/2018/10/01/the-professor-vs-the-nsa/

# Happy E Day! (British version)

Using the British day/month/year format of abbreviating dates, today is 2/7/18, matching the first four significant digits in the decimal expansion of .

Using the British convention, it’ll be Day again on 27/1/82, or January 27, 2082. I doubt I’ll personally be around to see that one, but I was alive to enjoy January 27, 1982. At the time, I was (barely) old enough to know the significance of the number , but I wasn’t old enough to know that other parts of the world abbreviate dates in a way different than Americans.

*Posted by John Quintanilla on July 2, 2018*

https://meangreenmath.com/2018/07/02/happy-e-day-british-version/

# Happy E Day!

In the United States, today is 2/7/18, matching the first four significant digits of .

The next time that this date can be celebrated is July 2, 2018 (using the day/month/year format of abbreviated dates.) After that, we’ll have to wait until 27/1/82, or January 27, 2082. (Sadly, I knew about the number back in 1982 but was then unaware of the day/month/year method of abbreviating dates, and so this day went unrecognized by me on January 27, 1982.)

*Posted by John Quintanilla on February 7, 2018*

https://meangreenmath.com/2018/02/07/happy-e-day/