Tag Archives: math

Engineer’s Rounding Joke

“pi=10, it also equals 3 and e=3 so pi=e!”
When talking about safety factors, the informant, an engineering student, shared the joke. Because engineers are always concerned about the safety of the users of their products (because getting sued is no fun) and like to account for the things more difficult to account for, one way to introduce a safety factor is to make pi equal to 10 in all calculations. This massive rounding then prompted the follow up of simply rounding e (~2.718) and pi (~3.14) could simply be rounded to 3 for simpler calculations and that error would be accounted for with the safety factor.
My Thoughts
This joke has some practicality to it by reminding engineers to have large safety factors to ensure the safety of their designs, it is also a joke on the rather flippant view of numbers that engineers have as it doesn’t always need to be precise but simply overkill enough for the application. I also relate this to the idea that engineers are lazy and so create processes and machines to ensure they can be lazy at the desired times. Multiplying or dividing by 10 is about as lazy as it gets in math.

Order of Operations Mnemonic Device

PEMDAS- Please excuse my dear Aunt Sally
The informant was introduced to this mnemonic device in late elementary school and middle school as a method to learn the order of operation: parentheses, exponents, multiplication, division, addition, and subtraction. When solving a mathematical equation, the order that one performs the operations is important to reach the final answer. The students were taught “Please excuse my dear Aunt Sally”; however, the informant and many other students in the class would change to simply say “Pemdas”, a made-up word, but one they could still remember. The phrase was less appealing to the informant and their peers as it was long and required them to break down the phrase into the first letters of each word to get the actual desired content.
My Thoughts
The students were taught the phrase “Please excuse my dear Aunt Sally” by their teachers, but instead made their own mnemonic device to better match their preferences. The shorter device may point to a desire for efficiency in those who use it as they prefer a more straight-forward learning method than one that might be seen as ‘creative’.

The Mathematician, The Physicist and the Engineer

The Mathematician, The Physicist and the Engineer

Informant: I’m a math-econ major so I was always highly interested in math, science, and engineering. I heard this from one of my math professors in high school. Weirdly it was one of my math professors or my religion teacher. So basically you have a mathematician, a physicist, and an engineer. And so they are all in separate classrooms and a fire breaks out in their rubbish pails simultaneously. Uh . . . I can’t remember which one was which, but the physicist calculates the exact amount required to put out the fire and then put outs the fire with very little mess. The engineer just dumps water on it to put out the fire and makes a huge mess. The mathematician on the other hand starts writing on the board, fills up one board, goes on to the next, fills up that one, goes on to the next, fills up that one, puts down his chalk and says, “it can be done, it can be put out”. And that’s basically the joke; it plays off of stereotypes of physicists, engineers, and mathematicians

Interviewer: How old were you approximately when you first heard it?

Informant: I was in high school so I was around 16-17 in Washington D.C

Interviewer: Do you tell it to other people?

Informant: Not really anymore, because I don’t remember it properly. I found it hilarious when I first heard it because I found it so true.

Interviewer’s notes:

This joke is a type of Blason Populaire. The humor of the joke plays off of the stereotypes of physicists as precise, engineers as messy, and mathematicians as over -thinkers. It is interesting to note that the informant is in the same field of study of the subjects of the joke which is indicative of why the informant is compelled to proliferate the joke. For the informant, the humor is enhanced by her ability to relate.

Student inadvertently solves never-before-solved math problems

My informant told me about a story she heard about a student waking up late and rushing to their final, then frantically trying to finish the three equations on the board. The first two weren’t so bad, but the third was difficult. He finally finished and turned it into the professor only to find out later the third was actually not part of the test. Instead, it was a problem that had as of yet been unsolved. He had figured it out, though. My informant likes it because she thinks it would be cool to accidentally become famous like that and because it relates to one of her favorite movies, Good Will Hunting, since the main character in it easily solves equations no else could.

I like how the story reflects how we believe what we hear; when we are told something is impossible, it will seem much harder in our mind. But when we think something is supposed to be solvable, it may be easier to figure out, even if it’s never been done before. Limitations we place on ourselves are often illusory.

I looked into the story and found that it is actually based in truth. In 1939, George Dantzig arrived late to his graduate statistics class and saw two problems on the board, not knowing they were examples of problems that had never been solved. He thought they were a homework assignment and was able to solve them. He found out the reality six weeks later when his teacher let him know and helped him publish a paper about one of the problems.

Annotation: Cottle, Richard, Ellis Johnson, and Roger Wets. “George B. Dantzig.” Notices of the AMS 54.3 (2007). Web. April 23 2012.

Riddle – American

Make the following equation true by drawing only one straight line:

5 + 5 + 5 = 550

Answer: 5 4 5 + 5 = 550

My informant saw this riddle on a Facebook wall post from her roommate.  She was bored one day and did not want to do homework, so she asked her roommate to give her something to do.  Her roommate posted this riddle on her Facebook wall.  My informant worked on the riddle for a very long time but could not figure out the answer.  Eventually, her roommate gave my informant the answer to the riddle.   It is interesting that my informant heard this riddle from an engineering major, since the riddle is a play on a math problem.

My informant believes this riddle is popular among math and engineering students as well as anyone who enjoys mathematics.  My informant also believes that because she could not figure out the riddle because she is not as skilled at mathematics as her roommate is.

I believe that figuring out this riddle has nothing to do with mathematics.  I think this riddle is visual.  Those who are very observant and visual people are more likely to solve this riddle.

Collector’s note:  How this riddle was shared demonstrates the influence of the Internet on the spread of folklore.