An Outliers Scarf for Jade

OutliersScarf3

I recently posted an explanation of my Probability Scarf, where I simply rolled a die to decide which of 6 colors to use for each row of the scarf.

Probability_Scarf

But that represents a uniform distribution, where each color is equally likely — a little boring.

So I thought: Why not make a scarf using the normal distribution, a bell-shaped curve. I searched the web and found a site that would give me random numbers generated from a normal distribution.

I’ll use four colors:

OutliersYarn

Brown is for the center of the distribution (numbers within half a standard deviation from the mean). This is where most of the data will fall.

The next color has a bit more red in it, but it’s between red and brown. This will be for numbers between a half and one standard deviation from the mean.

The third color will be used for numbers more than one standard deviation from the mean, but less than one and a half standard deviation. It’s quite bright and red and pretty.

And finally — for the outliers — I bought a rainbow yarn. It turns out it changes colors very slowly, so you can’t necessarily tell that it’s rainbow-colored in the scarf, but it is bright and is slowly changing.

Also, about half the numbers are negative and half positive. I went with positive is for purl and negative is for knit.

And the point of the scarf? It is the outliers that make it beautiful! Yes, we need the nice middle-of-the-road, close to the mean folks — but the colorful ones are the outliers and add spice to life.

I’m planning to give the scarf to my daughter Jade, who has always been an outlier in several areas — and I fully believe that has a lot to do with why she is so wonderful.

OutliersScarf2

The scarf is turning out lovely. I plan to continue until I run out of one color. (I bought two skeins of the brown yarn.) Yes, I am going to have lots of ends to sew in when I am done! I’m planning to do a crocheted edging in brown to cover up some of that.

OutliersScarf1

I’m gathering all my Mathematical Knitting links on my Sonderknitting page.

Fibonacci Swatchy

My sister-in-law is expecting a baby next June. Her toddler already has a Prime Factorization Blanket, and I just finished making a second one for a niece in another family. It’s time for something new!

Inspired by my Fibonacci Clock (not my idea, but a clock purchased via Kickstarter) and my Fibonacci Spiral Earrings, I’m thinking about making a Fibonacci Spiral Blanket.

Fibonacci Clock

The Fibonacci Sequence is simple. You start with 1, then each new number is the sum of the two numbers before it:

1
1 + 0 = 1
1 + 1 = 2
1 + 2 = 3
2 + 3 = 5
3 + 5 = 8
5 + 8 = 13
8 + 13 = 21
and so on. . .

I made a swatch to see if it would work, and I think it’s going to. Here’s the Fibonacci Swatchy:

Fibonacci_Swatchy

It starts with the little white square, which represents 1. I planned to make the blanket 12 stitches by 12 garter ridges. I made the swatch 6 by 6, and think I may go with that for the blanket after all. The important thing is for it to be divisible by 3. It’s going to get big fast.

Okay, after the initial square, I picked up stitches along one edge of the square. I added a new color for this square, but it’s the same size as the first, still representing 1. Since 1 = 1 + 0, I used the first color (white), but added a new color representing the new entry in the sequence.

For the next square, representing 2, I picked up 12 stitches along both the previous squares. I use three colors — representing the two numbers whose sum in the new entry. This pattern will continue. Each new Fibonacci number will get a new color of its own — but I’ll alternate that with the two colors representing the two numbers I summed to get this number.

And in garter stitch it turned out very cool if you alternate rows of three colors — It turns out that you will have the yarn waiting for you when you’re ready to pick up that color again on the correct side. And the garter ridges work out to look like solid stripes. There are two colors in between the ridges, but because of the way the texture works, you see the matching color ridges together.

So in the swatch, the entry representing 2 was a 12 by 12 square alternating white, pink, and burgundy.

For the next entry, representing 3, I picked up stitches along the square I just finished plus one of the 1 squares, so that made 18 stitches, and I went for 18 rows. I dropped the first color white, and now alternated pink, burgundy, and a new color, lavender.

To finish it off, I chain stitched in a golden Fibonacci spiral. For the actual blanket, I’ll be a little more careful to make each curve circular.

I think this may make a fine blanket. The squares will get big quickly, so I’m not sure how far it will go. My brother and his wife should find out the baby’s gender in January. Though I’m thinking even if the baby is a girl, I may want to use more gender-neutral colors in the middle (these starting squares) and save pink for the bigger squares that will come later. But we’ll see. I also learned a little bit by swatching about how I want to pick up the stitches. But the main lesson is that alternating three colors in garter stitch works great! And crocheting on a golden spiral works great!

This is going to be fun!

My posts on Mathematical Knitting and related topics are now gathered at Sonderknitting.

My Prime Factorization Hairnet

ModelingHairnet

Our church is having a Stop Hunger Now Food Packaging Event next Sunday, October 18, 2015. As a form of publicity for the event, they’ve asked us to decorate a hairnet and take a selfie.

That was the moment I realized: I have a Prime Factorization Sweater, a Prime Factorization Cardigan, a Prime Factorization Scarf, a Prime Factorization T-Shirt, and have made Prime Factorization Blankets. But I didn’t have a Prime Factorization Hairnet!

Well, I soon remedied that!

Hairnet

Okay, it’s not knitting. But I printed a chart I’d made of numbers color-coded with their prime factorization for the Prime Factorization T-shirt. Then I simply cut out the individual squares and glued them to the hairnet in a spiral pattern. So it goes from 1 to 100.

How it works? Each prime number gets a new color. Composite numbers are divided into sections with a section for each factor. Each section is colored according to that prime’s color. For example, 42 = 2 x 3 x 7, so the square for 42 is divided into three sections, colored blue for 2, red for 3, and green for 7.

This selfie not only shows the Prime Factorization Hairnet, it also gives a glimpse of infinity!

Hairnet+Infinity

Oh, and I’m gathering all my Mathematical Knitting (and other mathematical creations) at Sonderknitting. Eventually, I’ll add mathematical explanations and patterns and activities and other good things.

I can safely say that mine is the most educational hairnet selfie posted yet!

My Probability Scarf

Probability_Scarf

I’ve started collecting my Mathematical Knitting posts at Sonderknitting, a Mathematical Knitting Gallery.

But I’d never done a post about my Probability Scarf.

This is not my idea. I don’t remember where I saw the instructions, but they are easy and a lot of fun.

1. Choose six colors of yarn that go together well. Assign them numbers from 1 to 6.

I chose leftovers from my Prime Factorization Sweater.

2. You’ll be knitting a scarf the long way, using the ends as fringe. Start by casting on to a circular needle however long you want your scarf to be. (Try to keep it loose!)

3. For each row, roll a die to decide which color to use. Flip a coin to decide whether to knit or purl.

4. Continue in this manner until you’ve run out of one of the colors.

You now have a scarf demonstrating the Uniform Distribution.

This scarf was fun to knit. It was hard to stop knitting, because I kept wondering what the next row would look like.

It occurs to me that it would be fun to do a Probability Scarf using a different probability distribution. You could find a generator based on another distribution (where the colors wouldn’t all be evenly distributed) and use that to decide which color to use. This would be fun if you wanted to use a second or third color just for highlights. Or maybe you didn’t have the same amount of each yarn. Maybe that will be a future project….

My posts on Mathematical Knitting and related topics are now gathered at Sonderknitting.

Review of I See a Pattern Here, by Bruce Goldstone

i_see_a_pattern_here_largeI See a Pattern Here

by Bruce Goldstone

Henry Holt and Company, New York, 2015. 32 pages.
Starred Review

I love Bruce Goldstone’s books about math concepts. They are bright and colorful and draw kids in – and explain the math concepts in simple language, with helpful, dramatic visuals.

This one is about patterns. He explains them using simple language and has a little box giving the mathematical vocabulary where it’s appropriate. As in his other books, he starts simply and builds.

The book covers repeating patterns, then translations (“slides”), rotations (“turns”), reflections (“flips”), symmetry (“equal sides”), scaling (“changing sizes”), and tessellations (“tile patterns”). The many, many varied pictures make the concepts so clear.

For example, he uses photos of quilt blocks, tiles in the Alhambra, kaleidoscope images, lace patterns, tire treads, animals, architecture, beads, stamped patterns, and a 2000-year-old Peruvian cloak.

This is a beautiful book that will get kids noticing the patterns around them and give them a new vocabulary for talking about those patterns.

brucegoldstone.com
mackids.com

Buy from Amazon.com

Find this review on Sonderbooks at: www.sonderbooks.com/Childrens_Nonfiction/i_see_a_pattern_here.html

Disclosure: I am an Amazon Affiliate, and will earn a small percentage if you order a book on Amazon after clicking through from my site.

Source: This review is based on a library book from Fairfax County Public Library.

Disclaimer: I am a professional librarian, but I maintain my website and blogs on my own time. The views expressed are solely my own, and in no way represent the official views of my employer or of any committee or group of which I am part.

What did you think of this book?

Review of If . . . by David J. Smith

if_largeIf . . .

A Mind-Bending New Way of Looking at Big Ideas and Numbers

by David J. Smith
illustrated by Steve Adams

Kids Can Press, 2014. 40 pages.

The author of the brilliant If America Were a Village is at it again, using scale to give children a feeling for enormous numbers. Here’s what he says on the first page:

How big is Earth or the Solar System or the Milky Way galaxy? How old is our planet and when did the first animals and people appear on it? Some things are so huge or so old that it’s hard to wrap your mind around them. But what if we took these big, hard-to-imagine objects and events and compared them to things we can see, feel and touch? Instantly, we’d see our world in a whole new way. That’s what this book is about – it scales down, or shrinks, huge events, spaces and times to something we can understand. If you’ve had a doll or a model airplane, you know what scaling down means. A scale model is a small version of a large thing. Every part is reduced equally, so that you don’t end up with a doll with enormous feet or a model plane with giant wings. And when we scale down some really huge things – such as the Solar System or all of human history – some of the results are quite surprising, as you are about to see…

The book goes on to look at such scenarios as:

If the Milky Way galaxy were shrunk to the size of a dinner plate…
If the planets in the Solar System were shrunk to the size of balls and Earth were the size of a baseball…
If the history of the last 3000 years were condensed into one month…
If the inventions of the last 1000 years were laid out along this ruler…
If all the water on earth were represented by 100 glasses…
If all the wealth in the world were represented by a pile of 100 coins…
If average life expectancy (the number of years people live) were represented by footprints in the sand…
If today’s world population of over 7 billion were represented by a village of 100 people…
If your whole life could be shown as a jumbo pizza, divided into 12 slices…

With each scenario, graphics on a double-page spread show how the hypothetical object would be divided up, with some surprising results.

In the your-life-as-a-pizza example, 4 of the 12 slices would be work and school and 4 of the 12 slices would represent sleeping. In the wealth example, we see one person standing on top of a pile of 40 coins, 9 people on top of the next 45 coins, on down to 50 people standing on the one lone last coin. With footprints in the sand, we see the footprints from some continents don’t go nearly as far as those from others.

The population example may be the most interesting, because the author goes back in time. If today’s population were represented by a village of 100 people, the village in 1900 would only have 32 people, in 1500 only 8 people, and in 1000 BCE, there would have only been 1 person.

kidscanpress.com

You get the idea: These ideas and images give you a grasp of the large proportions between these things and a handle for understanding enormous numbers.

Buy from Amazon.com

Find this review on Sonderbooks at: www.sonderbooks.com/Childrens_Nonfiction/if.html

Disclosure: I am an Amazon Affiliate, and will earn a small percentage if you order a book on Amazon after clicking through from my site.

Source: This review is based on a library book from Fairfax County Public Library.

Disclaimer: I am a professional librarian, but I maintain my website and blogs on my own time. The views expressed are solely my own, and in no way represent the official views of my employer or of any committee or group of which I am part.

What did you think of this book?

Pascal’s Triangle Shawl #2

Hooray! Hooray! Today I finished my second, prettier Pascal’s Triangle Shawl!

PTwhole

Pascal’s Triangle is the triangle with 1s on the edges, where each entry is the sum of the two entries above it.

So the beginning rows work like this:

1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
1 6 15 20 15 6 1
1 7 21 35 35 21 7 1

1to5

Now, what I did was choose a color of yarn for each prime. Then each entry in the triangle is factored, and each number is shown by the colors of its factors.

I did the same thing with my first Pascal’s Triangle Shawl. With this one, since there are only the primes 2, 3, 5, 7, 11, and 13, I decided to use progressively darker shades of pink and purple, so the shawl would gradually get darker.

Here is a closer look at a section of the shawl:

Right Side

This next picture shows that along the second row, we have the numbers simply in sequence.

Right and Top

For math nuts, each row also contains the binomial coefficients, the coefficients in the expansion of
(a+b)^n

This means that the rth entry in the nth row can be calculated with the formula:
n!/(n-r)! (Counting the entries in each row as 0 through n.)

Some examples: The 2nd entry in the 5th row is (5×4)/(2×1) = 10

The 3rd entry in the 7th row is (7x6x5)/(3x2x1) = 35

Now, I factor all the numbers in my shawl, so for big numbers, it doesn’t matter what the actual number is, but the factorization is easy from the formula.

For example, the 4th entry in the 15th row is (15x14x13x12)/(4x3x2x1) = 3x5x7x13

You can see some of the bigger numbers in this picture:

Right Factored

Now, there are a couple of characteristics which I believe make the shawl especially beautiful.

One is that because these are the binomial coefficients, once you get to the row of a prime number, every entry in that row has the prime for a factor.

This is easier to see with the actual shawl in front of you, but here again is the big picture. You can see that once a new color starts, it goes all the way across the row.

PTwhole

What’s more, by the distributive law, since every entry in a prime row has that prime as a factor, all the sums of those numbers will also have the prime for a factor — and we end up having inverse triangles of each color.

Here’s some more detail:

Detail2

Detail1

Of course, the very coolest thing about it is that, even if you have no idea of the math involved, the combination is beautiful.

And that simply makes me happy.

Modeling Shawl

My posts on Mathematical Knitting and related topics are now gathered at Sonderknitting.

Crazy 8s Math Club and Living Venn Diagrams

This week I brought my camera to Crazy 8s Math Club! We were learning about Sets and Venn Diagrams – and look at those faces!

Crazy 8s is a Math Club sponsored by BedtimeMath.org. They provide the ideas and materials, and the library provides the place.

Here is a set of kids with brown eyes. We had a Flat Visitor from California who also had brown eyes!

Crazy8s1

When we started the 3-set Venn diagram, I thought they could start with cars and trucks. They caught on quickly!

Crazy8s2

And finally, a living Venn diagram. The kids figured out where they belonged depending on whether they had brown eyes or not, whether they could curl their tongue or not, and whether they fold their hands with their left or right thumb on top. I’m happy to say that the kids who didn’t fit in any of those sets were excited to be “in the universe.”

Crazy8s3

And afterward — some silliness with the glowsticks (which they got to take home).

Crazy8s4

Crazy8s5

Crazy8s6

More proof that Math is Fun — and kids know it!

Review of Really Big Numbers, by Richard Evan Schwartz

really_big_numbers_largeReally Big Numbers

by Richard Evan Schwartz

American Mathematical Society, 2014.
Starred Review
2014 Mathical Books Award Winner

Full disclosure: When I visited the National Math Festival and met Richard Evan Schwartz, I got all fangirl about his book You Can Count on Monsters and showed him my prime factorization cardigan. Of course I purchased his new book and got it signed. I am particularly proud of what he wrote: “To Sondy, Beautiful cardigan! It looks like we have a lot of the same ideas. Best wishes, Richard Schwartz”

And when I showed him my Pascal’s Triangle Shawl, he gave me the idea of making a new one using congruences mod n. Yes! I like the way this man thinks!

[In fact, in a weird side note, after reading his bio on the AMS webpage and learning he did his undergrad in math at UCLA, I find myself with a memory — which very well may be false — of taking a class with him as an undergraduate when I was a graduate math student at UCLA. I took a class (Number Theory?) with some undergraduates. That was in 1985-1986. An internet search shows he got his PhD in 1991 — so this is actually possible! And I remember a cocky and extremely intelligent student who looked a whole lot like he does now, only younger….]

You will not be surprised when I say I loved his new book! There are many books that deal with large numbers using analogies. A few from the beginning of this book include:

About 7 billion people live on Earth. If they all lined up, spaced about a foot apart, they would circle 50 times or so around the equator.

You could cram about 20 billion grains of very fine sand into a basketball.

100 billion basketballs would fill New York City roughly to the height of a man.

You could cover the service of the earth with about a quadrillion (10^15) exercise trampolines.

A quintillion (10^18) grains of very fine sand would just about cover Atlantic City, NJ, to a depth of 3 feet.

Speaking of a quadrillion and a quintillion, I’ve seen a few other books that explain the names for large numbers, but that’s only about the halfway point of this book! You know things are getting interesting right after the page where he shows

10^21 sextillion
10^24 septillion
10^27 octillion
10^30 nonillion
10^33 decillion

The next page says, “This system goes quite far out but I think that these names lose their novelty after the first 30 or so.” On that page we see spectators sleeping or reading a newspaper. Here’s the chart:

10^36 undecillion
10^39 duodecillion
10^42 tredecillion
10^45 quattourdecillion
10^48 quindecillion

On the page facing that one, he says, “Here, let me skip ahead some and show you the names of a few really big ones.”

10^78 quinquavigintillion
10^93 trigintillion
10^108 quinquatrigintillion
10^123 quadragintillion
10^153 quinquagintillion

Since this is still only about the halfway point of the book, you get the idea that when this book talks about really big numbers, it means really big numbers!

The author throws in questions about the big numbers – questions challenging enough to get even an adult with a math degree thinking.

There are more illustrations of the size of things, such as:

The sun, the true giant in the solar system, has about 4 nonillion (4×10^30) pounds of material.

We could continue counting up roughly by powers of 1000, moving out beyond the solar system to the stars surrounding the sun and eventually to galaxies and galaxy clusters, and superclusters, outward even to supercluster filaments and membranes…

but if you want to see some REALLY big numbers, we will have to move faster than that.

What is this author’s idea of REALLY big numbers? Well, before long, we get to a googol (10^100).

A googol atoms would fill the observable universe about 100 quadrillion times over.

You could say that a googol is so big that it rises beyond the merely astronomical.

He gives more illustrations of how big a googol is, but then says:

Yeah, a googol is a pretty big number.

But if you want to talk about REALLY big numbers then we’ll have to move on to a new level of abstraction. So, get ready, because the ride is gonna be pretty bumpy from here on in. But, remember, this book is supposed to be like a game of bucking bronco and you can always come back to it later if you fall off now.

All of this is accompanied by helpful and/or amusing computer cartoon illustrations.

So, then, the first abstract thing I want to tell you about is called plex.
When you “plex” a number, you write 1 followed by that number of zeros.
In other words, when you plex a number, you raise 10 to that power.

A googol-plex is 1 followed by a googol zeros, or, equivalently, 10 raised to the googol power.

A googol-plex is also 100-plex-plex and likewise 2-plex-plex-plex.

I love this page:

In my experience it is impossible to picture a googol-plex in concrete terms. Any attempt will scramble your brain. An implacable guard blocks the door to that kind of intuition.

But, let’s try to sneak by the guard and see what we can.

After some attempts at that, he says:

Mathematics gives us a language to name all kinds of things, but we can’t relate to everything we can name. If you want to think about REALLY big numbers, you have to give up the idea of picturing them….

Just let go of the reins and let LANGUAGE gallop on.

He even explains Recursion – “the trick of making something new by applying a simple rule over and over.”

Then he looks at some numbers plexed multiple times. I just love when he starts making up his own names.

Here is the number “one plexed one plexed two times times.” [The diagram here is very helpful.]

This number has no familiar name, so let’s call it “Fred.”

Let’s unravel “Fred” from the inside out.

“one plexed two times” is 1010, or ten billion, so “Fred” means “one plexed ten billion times.”

And here is “1 plexed FRED times.”
Let’s call this number “Big Jim.”

You may ask, “How big are ‘Fred’ and ‘Big Jim’?”

I’ll tell you honestly: I don’t know! Already, “1 plexed 4 times” makes a googol-plex seem microscopic, and each new plex is a quantum leap forward in size and abstraction.

To get to “Fred” you take 10 billion quantum leaps.
And “Big Jim” is “Fred” quantum leaps away.

And Richard Schwartz still doesn’t stop there! At the end of the book, he starts introducing new symbols. He shows a square that means “1 plexed N times.” Then he makes a new symbol that builds off of the square, and further symbols that build off of that.

Accompanied by diagrams with these new symbols, he says:

Once you get a taste for this kind of symbol, and the accelerated voyage it lets you take through the number system, nothing stops you from making more symbols.

Each new addition to the language is a chariot moving so quickly it makes all the previous ones seem to stand still.

We skip from chariot to chariot, impatient with them almost as soon as they are created.

Unhindered by any ties to experience, giddy with language, we race ever faster through the number system.

When you finally reach the last page, you will agree with the final line:

Infinity is farther away than you thought.

I’ve quoted extensively from this book, but believe me, quotes out of context pale in contrast with the actual book – I’m simply giving you a clue as to what you’ll find here. The illustrations, symbols, and diagrams all help lead the train of thought, or I should say ladder of thought, or better yet supersonic jet of thought.

I wish I had this book when my boys were young! My oldest, when he was in Kindergarten, liked to make up words for numbers “bigger than infinity.” I think the way this book is presented, the ideas of larger and larger numbers – bounded only by your imagination – would have inspired both my sons. I definitely plan to show this to kids at the library.

ams.org/bookpages/mbk-84
mathicalbooks.org

Buy from Amazon.com

Find this review on Sonderbooks at: www.sonderbooks.com/Childrens_Nonfiction/really_big_numbers.html

Disclosure: I am an Amazon Affiliate, and will earn a small percentage if you order a book on Amazon after clicking through from my site.

Source: This review is based on my own copy, purchased at the National Math Festival and signed by the author.

Disclaimer: I am a professional librarian, but I maintain my website and blogs on my own time. The views expressed are solely my own, and in no way represent the official views of my employer or of any committee or group of which I am part.

What did you think of this book?

Super Pi Day at City of Fairfax Regional Library

Today was Super Pi Day! 3.14.15, celebrated especially between 9:26:53 am and 9:26:53 pm.
(My son says it should be called Slightly-More-Accurate-Approximation-of-Pi Day, but I’m going with Super Pi Day.)

PiDay1

I got my geek on, with my Floating Point Pi Earrings from ThinkGeek, my Pi t-shirt from the Mathematikum in Giessen, Germany, Apple Pi socks, and of course my Prime Factorization Cardigan. I also brought in a Chocolate Angel Pi Pie.

My favorite comment was when I was explaining all this to one of the Library Friends. She said, “It’s good to see someone who loves what they do.” My translation: “You really are a Math Geek.” Yes, I am. Yes, I am.

Since a Children’s Used Book Sale was going on all day, we couldn’t use the meeting room, and decided to run an all-day Pi Day Scavenger Hunt.

Scavenger Sign

Participants only needed to answer 8 of the 10 questions, and we hoped they’d be pulled into the library to answer them. They were to write the answer on the pie piece, and get a prize when all the pieces were filled in. These were the questions:

1. For any circle, pi equals the circumference of the circle divided by what?
2. Albert Einstein was born on March 14th. What famous equation did he write?
3. Some people think we should celebrate Super Pi Day next year. Why is that?
4. What library number would you look under for books about pi?
5. What library number would you look under for books about pie?
6. List another irrational number.
7. What U.S. city has the zip code 31415?
8. Find a book in the library with “circle” in the title. List the title.
9. What letter comes after pi in the Greek alphabet?
10. Someone in the library is wearing a prime factorization sweater. What is her name? (Hint: You can google it.)

The prize was a wristband from thepidayofourlives.homestead.com celebrating Pi Day, along with some circular candies.

We ordered 57 wristbands. A hat came along with it, and none of my coworkers wanted to wear it, so I added it to my Pi gear:

PiDay2

Response was wonderful! By the end of the day, we’d given out 56 wristbands! I loved watching the kids working to figure out the answers. And I’ve never gotten the chance to talk to so many people about my prime factorization sweater all on the same day!

I admit this family, with Super Pi, Pi a la mode, and a Pi-rate, were my favorites:

Customers

But overall, it was simply a huge success!

I was going to fill in the answers, but instead, why don’t you add them in the comments if you know the answers? 🙂

Happy Happy Slightly-Better-Approximation-of-Pi Day!