My day job colleague told a beautiful story yesterday. He had been washing his car late at night, in the dark, and was approached for assistance. He is generous beyond belief, and apparently he made a real impact.
I was washing my car the other night and really getting after it. I had the scrubbing brush going and was really making progress on getting the car clean. I was totally focused and I felt a tap on my shoulder. It startled me and I turned around to be faced with a large African-American woman who said, “I’m sorry, I don’t mean to interrupt, but we’re having car problems. Is it possible you can help us? I think we need the battery jumped.”
I looked down the street and saw no other people and no car. Within a split second I remembered my latest purchase: a wireless battery charger that needs no people, no cables and no extra car to jump a battery. I got it out of my garage and handed it to her.
“I’m in the middle of washing my car. Why don’t you borrow this? It should help.”
She thanked me and walked away with the charger. I got back to washing my car.
Five minutes later there was another tap on my shoulder. Another African American woman was standing there holding a five dollar bill. She offered it to me.
“Oh my goodness, no,” I said. “I’m not taking your money. I’m just glad I could help.”
Another 5 minutes went by and I saw one of the ladies put the battery charger close to my garage. I was really getting into the car washing at this point – suds everywhere – so I didn’t pay much attention.
When I was returning my carwash supplies to the garage, I saw a crisp new $100 bill on top of the battery charger!
That thing was only $40 – and they just gave me $100 to borrow it!
This is a wonderful and touching story. These ladies were having difficulty finding someone to help them. Not only did my friend help, he also freely gave them something to use and trusted without question that they would return it.
They, too, were moved by his generosity.
The numbers don’t work.
It looks like this:
Battery charger cost: $40
“Rental fees” offered: $5
Shown gratitude: $100
The numbers don’t make sense. And in a way they shouldn’t. The $100 bill wasn’t really money. It was the biggest, fattest, loudest thank you note ever written. There’s no value you can place on someone being free and generous and trusting.
It still goes in as $100 in the eyes of the bank. But what do they know?
Notice the math and share the story.
When you share this story, point out the math. Especially if you tell this in front of (or to) children. Making the connection of generosity and emotion to math will help everyone see how integral math is in our lives.
How about you? Do you have a story of generosity that you’re just now realizing involves math? Share it in the comments!
We had a fun little discussion via email at the day-job. Someone changed the code on the combination lock and the discussion around combinations, permutations, cryptography and all things sneaky-math cranked up.
It reminded me of this neat fact I learned about credit card security.
Not all digits on a credit card are created equally!
A credit card is made up of 16 numbers. But only the first 15 are “random,” according to NRich Math. The last number – the 16th number – is the “check digit.” It’s calculated using a fancy formula using the first 15 digits.
This check digit helps a computer system quickly determine if a credit card number is fake. Now, it can’t confirm that it’s real – it just can help determine if it is fake.
The digit is created using a method called Codabar.
First, let’s define some things.
An odd digit is a digit in the credit card number that is in an odd position. For the photo of the card here, the number is: 5184 8204 5526 6423:
The odd digits are 5, 8, 8, 0, 5, 2, 6, 2
An even digit is a digit in the credit card number that is in an even position. For the photo of the card here, even digits are 1, 4, 2, 4, 5, 6, 4, 3
The check digit is the last digit – it gets calculated and isn’t considered in either odd or even position. It’s a super special digit.
The method is weird – and kinda fun!
Here’s what you do:
Add up all the odd digits, or the digits in the odd positions: 5 + 8 + 8 + 0 + 5 + 2 + 6 + 2 = 36
Double that number: 36 × 2 = 72. Save this number, 72, for later…
Add the even digits together, or the digits in the even positions: 1 + 4 + 2 + 4 + 5 + 6 + 4 + 3 = 29. Save this number, 29, for later…
(This is a freaky step.) Count the number of odd digits that are greater than 4. The odd digits are 5, 8, 8, 0, 5, 2, 6, 2. Of these, 5, 8, 8, 5 and 6 are bigger than 4. There are 5 of those total. Save this number, 5, for this next step…
Add up the results you saved from steps #2, #3 and #4. 72 + 29 + 5 = 106
Take the answer from step #5 and figure out how many you need to add to get it to the next multiple of 10 (or the next number that ends in zero). The number after 106 that ends in zero is 110. So we need to add 4. 106 + 4 = 110. 4 is the super important number.
That final super important number – well, that’s the check digit! That’s the last number that should be on the credit card – if it were a real card!
For the picture, the check digit should be a 4. And it’s a 3. So I can tell instantly that this is a fake credit card number.
For many across the world, today is the first day of school. For after schooling families, or blended homeschoolers going to a co-op, you’ve probably been shopping for new clothes for a few weeks. For those in areas that offer tax-free back-to-school weekends, you no doubt have taken advantage of that. Even if you unschool on a sailboat hopping around the coast!*
And why should the children have all the fun? Why not do a little back-to-school shopping of your own?
And of course, don’t just buy any clothes, buy math clothes!
Math accessories dress up a business or formal look.
At a fancy business meeting, or a full tilt gala, show your affinity for math with your jewelry. This Fibonacci sequence necklace is a beautiful addition to the little black dress or business suit:
Notice the Fibonacci sequence: 1, 1, 2, 3, 5
This artist is working with me to create some really neat Fibonacci earrings and matching bracelet. We’re also working on other patterns and concepts for jewelry that says, “Math is cool, and it’s pretty too!”
Business casual means t-shirt with a blazer.
My favorite outfit is a math T-shirt with a blazer over the top. I wear some slacks and modest heels and I’m ready to take on the world. Here’s a T-shirt that I found that’s on its way to me now:
This “obtuse” shirt is created by Matt at ExBoyfriend Collection (now BoredWalk), who is generous enough to give one to me! I’ll post a photo in full dress when it arrives.
It reminds me of what my Ma used to tell us: “Quit being so obtuse!”
Matt creates other math t-shirts too! We’re looking at collaborating on some – so keep your eyes peeled.
Take it to the limit with casual wear.
You can also wear a t-shirt as just a t-shirt, with shorts or capri pants.
This infinity shirt is from Mike who publishes MathFail, Spiked Math Comics and Math Shirts.
What’s your favorite math outfit? Are you hitting the stores for yourself this back-to-school season? Share with us in the comments!
* BTW, that’s my homeschooling dream – on a sailboat, unschooling around the coast!
Last night was taco night and my job was to grate the cheese.
I didn’t get too far in before I noticed some math.
For some reason I always start grating on a corner. Then I rotate the block so I’m grating on another corner. After doing this a few times I noticed the angles I was creating:
And what exactly are the shapes, anyway? What is the shape of the grating holes of the grater? And what is the resulting shape of the cheese sliver?
How much cheese is in the pile after you “fluff” it by grating it? What’s the volume of fluffed cheese compared with stuck-together-in-a-block cheese?
More importantly, is there enough for two grownups and a toddler? (When one of the grownups loves cheese!)
I had the pleasure of assisting Sarah Shah in her appearance on Great Day Houston yesterday.
While preparing for the show, I observed Sarah and the host, Deborah Duncan, in the makeup room having a conversation about math.
When I said to Sarah later, “that was an interesting math conversation,” she looked at me with anticipation, encouraging me to share what I heard. She had no idea I was referring to her conversation!
The math conversation was fully on-topic.
It was national thrift store day, and Sarah was going to share with GDH viewers some tips on shopping at resale shops. The topic of the show inspired their kibitzing behind-the-scenes about buying gold jewelry.
Deborah was talking about how there’s a difference (sometimes big) between the cost of the gold in a piece of jewelry, and the sale price.
The cost of craftsmanship should be close to its value.
Deborah was making the point that there’s value on the design of an object based on the workmanship that went into it. And this goes only so far.
Right now gold prices are around $1700 per ounce. Since an ounce is around 28 grams, gold is valued at about $60 per gram.
The QVC bracelet in the picture is 9 grams. It’s selling for $530 – pretty much exactly the value of the gold contained within.
If the value of gold for a 9 gram bracelet is around $530, charging $3000 for it means you’re paying about $2500 for the craftsmanship!
Unconscious math is all around.
Aqua And Gold Fractal by Sharon Apted
It was a wonderful experience to see two intelligent, educated women having a lively and entertaining conversation about math. It was quite disheartening, though, that Sarah didn’t even recognize it. In a previous life she was a physicist.
How many other conversations about math are ignored? How many people who claim they aren’t good at math have these conversations every day?
Look around at your conversations this week. How many of them are about math? Share your conversations in the comments. And with your kids!
Our discussion on fractions and pizza on #mathchat yesterday reminded me of a story.
Image via Wikipedia
My best friend lost on this deal back in 1978. But she gained a valuable lesson.
My friend, let’s call her Linda…
She was a terribly terribly slow eater. Like annoyingly so.
We would sit down to a Totino’s pizza on a summer afternoon. I would finish my half while she was still working on her first piece!
One day I suggested a different method.
“Let’s NOT divide the pizza in half – equally,” said I in my sweetest voice. “We’re best friends, and dividing food up is so primal. Let’s just eat like normal people.” (Okay, I’m sure I didn’t say, “primal,” but you get the point.)
She agreed. Even though she could manipulate the heck out of me, I certainly had my share of the talent.
She got two pieces.
A whopping 1/4 of the pizza.
She still tells this story.
And guess what? She totally knows the difference between her 1/4, our 1/2 and my 3/4.
What about you? Do you have any lessons you learned from friends in math? Share them in the comments.
Please note that my bottom still reflects this bad pizza eating habit. Perhaps writing it down for the world to see will help me knock of the over-pizza-eating habit. That and the LoseIt! iPhone app.
Everyone’s getting back into the schooling groove. So twitter is filled with questions like Cara’s:
And since my world revolves around math, here are my thoughts.
Use the Four Color Theorem (but don’t say it out loud).
The Four Color Theorem says that if you only have four crayons, you’re good to color your map and not have any colors touching. (That’s the he kiddo version of the theorem.)
So get out your google and print out some map coloring pages. Choose ones with lots of borders. (As fun as it is to color Texas as a whole, use a map of Texas’s counties.)
Caution: don’t tell the children they’ll be using math. Let them figure it out.
Now it’s coloring time!
And here’s the challenge: color the map with as few colors as possible so that no two touching territories have the same color.
While they color, you can talk about the names of the locations and some of the details. Even have them label them.
Once they finish coloring, have them remember how few colors they used.
Next time you talk about this map, ask them to use one less color than they did before. Continue labeling and discussing the locations.
After a while they’ll figure out that they can’t do it with three, but they can do it with four.
Shower, rinse, repeat.
From the Texas Environmental Education Providers (how cool is that!)
Kids are experimental. And they don’t believe that what works once, automatically works again (that’s why they drop Cheerios on the floor over and over and over again).
So you can do this with the next map when you’re ready to go to another part of the world.
Indeed, they’ll eventually figure out that four is the magic number. Then they can google it and learn all about the theorem!
How about it? Did it work? Share your experiences in the comments.
