## Two New Prime Factorization Blankets

I got two new great-nephews in 2022!

They are both second sons of their families. I didn’t knit their older brothers’ new blankets because I had barely finished my nephew Martin’s blanket, and they came so close together, I settled for two little cardigans.

But for Kellen and Tobi, I decided it didn’t matter if I was late finishing (and I was) — they needed Prime Factorization Blankets!

The idea is the same as my first Prime Factorization Blanket for Arianna:

Rows of Entrelac squares (or diamonds), going from 1 to 99. 1 is white and I put rows of white squares in between the rows with other numbers. After 1, every prime number gets its own color. For composite numbers, I put sections of the colors for each factor. So 4 gets two sections of 2, 6 gets a section of 2 and a section of 3, and so on, all the way up to 99, which gets two sections of the color for 3 and one section of the color for 11.

Kellen is modeling his blanket in the picture above, and here are some more pictures of it.

First the blanket as a whole. I knew he was a boy, so I used lots of blues, with 2 being yellow.

The corner at the start with the missing square for zero:

And the right bottom corner with some numbers labeled:

I don’t think I knew Tobi’s gender when I started his blanket, and I decided to try for bright colors instead of pastels, so 2 was red. Here’s the whole blanket:

Detail for the lowest numbers:

Detail for the highest numbers:

And some primes at the top of the blanket:

So much fun! (Tobi’s parents, if you read this, I need more pictures of Tobi modeling his blanket!)

And yes, I’m happy to report that my youngest sister is now expecting a baby, and he’s going to get a prime factorization blanket, too! I learned tonight that he’s a boy, so 23 is going to be blue.

Babies and math are beautiful!

## Mathematical Colors and Codes, Episode Six — Binary Codes and Booktalks

Episode Six of Mathematical Colors and Codes, my Virtual Program Series for the library is up!

Episode Six now looks at the Base Two number system, binary, and puts that into a code. To finish up the series, I talk about more books that play with mathematical ideas.

Like all the other videos in the series, this one has a downloadable coloring page. This one has a chart for a Binary Code.

Here’s this week’s video:

Here are links to the entire Mathematical Colors and Codes series:

## Mathematical Colors and Codes, Episode Five — More Codes with Nondecimal Bases

Episode Five of Mathematical Colors and Codes, my Virtual Program Series for the library is up!

Episode Five looks at more ways you can use nondecimal bases to make coded messages.

This video, like all the others has a downloadable coloring page. This one has charts for a Base Six Code and a Base Five Code.

Here’s this week’s video:

Here are links to the entire Mathematical Colors and Codes series:

## Mathematical Colors and Codes, Episode Four — Color Codes with Nondecimal Bases

Episode Four of Mathematical Colors and Codes, my Virtual Program Series for the library is up!

Episode Four now takes the Nondecimal Base systems we talked about in Episode Three and uses them to make coded messages.

This video, like all the others has a downloadable coloring page. This one has a chart for choosing your own colors and making your own coded messages with nondecimal bases.

Here’s this week’s video:

Here are links to the entire Mathematical Colors and Codes series:

Episode One, Prime Factorization
Episode Two, Prime Factorization Codes
Episode Three, Nondecimal Bases
Episode Four, Color Codes with Nondecimal Bases
Episode Five, More Codes with Nondecimal Bases
Episode Six, Binary Codes and Booktalks

## Mathematical Colors and Codes, Episode Three – Nondecimal Bases

Episode Three of Mathematical Colors and Codes, my Virtual Program Series for the library is up!

Episode Three is the longest episode. (They do get shorter!) I talk about various bases and look at them together with prime factorization color charts. I’m hoping it gives kids a feel for how other bases work.

This video, like all the others has a downloadable coloring page. [Right now this is the incorrect link. I’ll fix it with the correct one tonight.] This one will let you see for yourself how prime factorization patterns change in other bases, as well as giving you a feel for how counting works in other bases.

Here’s this week’s video:

Here are links to the entire Mathematical Colors and Codes series:

## Mathematical Colors and Codes, Episode Two: Prime Factorization Codes

Episode Two of my Mathematical Virtual Program Series is up!

In Episode Two, I talk more about prime factorization and ways to show it with colors. Then I show how you can use that idea to make a prime factorization code.

Here’s this week’s video:

Here are links to the entire Mathematical Colors and Codes series:

## Mathematical Colors and Codes

My Mathematical Virtual Program Series is up!

This program is a series of six videos with downloadable coloring pages. New videos will post on Mondays at 3 pm.

They will show kids how to use math to make colorful patterns and coded messages, learning about prime factorization and nondecimal bases along the way.

They’ll post on Fairfax County Public Library’s website, but I’ll post them here as well.

These will be best for kids who already understand multiplication.

And this week, Episode One is up! It covers Prime Factorization, with an explanation of my Prime Factorization Sweater. And it explains how you can color your own chart, using this downloadable coloring page.

I hope you enjoy it!

Here are links to the entire Mathematical Colors and Codes series:

## Normal Distribution Scarf

Today I finished a second Normal Distribution Scarf.

The first one I made was designed to highlight outliers to show that outliers are what makes the world beautiful.

For this one, I only wanted to show the Normal Distribution. I decided to knit it the long way so this time I wouldn’t have to sew any ends in.

I took colors from light to dark, in shades of pink. Colors B and C were a little closer than I wanted them to be, but it still gave the idea.

I generated numbers from a normal distribution and made a big list. For positive values, I purled the row, and for negative values, I knitted — so those values should be about even, making random ridges.

For the color, I used the absolute value, from light to dark. Since the normal distribution is a bell curve, there should be many more values in the lighter colors.

For 0 to 0.5, I used White.
0.5 to 1.0 was Victorian Pink.
1.0 to 1.5 was Blooming Fuchsia (only a little darker than Victorian Pink).
1.5 to 2.0 was Lotus Pink — a bright, hot pink.
Above 2.0 was Fuchsia — a dark burgundy.

Naturally, I used a lot more of the lighter colors. So for my next project after my current one, I think I’m going to do another normal distribution scarf, but this time reversing the values. So the new scarf would be mainly dark colors with light highlights.

In fact, if I weren’t using pink (maybe purple or blue), it would be fun to make scarves for a couple this way. Use dark, staid, sedate colors for the man, with light highlights. Use pastel shades for the woman — with dark highlights. [Hmmm. If I knit a scarf for a boyfriend before he exists, would the boyfriend jinx not apply?]

In this version, the lighter colors were more prominent.

Here’s a view of the scarf draped over my couch, showing both sides.

The different look has to do with where the knits and purls were placed and which side has a ridge and which is smooth.

Here’s a closer look:

I like the way the color combinations turned out so pleasing.

The only real problem is that the scarf is made out of wool, and it was almost 100 degrees outside today. So for now, I’m going to have to enjoy it draped over my couch rather than wearing it. I’ll look forward to this winter!

Update: I made an opposite scarf to this one, also generating random numbers and using the same exact yarn, but going from dark to light. Together, they make a matched set, so I gave them to my daughter and her wife-to-be!

## Prime Factorization Coloring Sheets

I’ve posted several Prime Factorization Coloring Sheets on my Sonderknitting page lately.

I decided I should try coloring them myself, so I could post a thumbnail of each one. I had a lot of fun doing it, and was reminded of lots of cool properties I discovered from knitting my prime factorization sweater and looking at these charts.

I have a manuscript for a math-related children’s nonfiction book about using math to make codes with colors. Originally, I put several of these charts into the book — but I eventually decided it was a distraction and decided to put them on my website instead.

But they show all sorts of cool things!

First, there’s the ten-by-ten prime factorization chart using ordinary, decimal numbers.

Coloring this chart gives you a great feeling for factorization and multiples. I posted about watching a second grader color it. I think of it as more for older kids, who are learning about primes and multiples, or indeed adults, in keeping with the adult coloring book craze. But watching a second grader color it assured me that it can give insights to anyone. (I made the instructions such that you don’t even have to know how to multiply. Just color every second square the color for 2, every third square the color for 3, and so on.)

Now, in my original sweater, I put rows of 8 on the back and rows of 2 and rows of 3 on the sleeves. The prime factorization charts in different bases are the same idea.

First, they give you a feeling for how different bases work.

Here’s the sheet for octal, base 8:

You can color it exactly the same way as you did the ten-by-ten chart. Color every second square with the color for 2, every third with the color for 3, and so on. If you take the time to do that, you’ll grasp how the numbers count up to 7 and then use the next digit, since place value in octal gives the ones digit, the eights digit, and the sixty-fours digit.

The chart also makes a good way to translate between octal and decimal. (Though you can just multiply the eights digit times eight and add the ones digit.)

But I enjoy some of the other patterns.

The first, most obvious pattern is that in the decimal chart, the multiples of 5 and the multiples of 2 line up vertically (as well as the multiples of 10, which are both). That’s because 10 = 2 x 5.

In the octal chart, the multiples of 2 line up vertically, since 8 = 2 x 2 x 2. So do the multiples of 4 — each with two factors of 2, and the multiples of 8 — each with three factors of 2.

In the Base 6 chart, as you’d expect, the multiples of 2 and the multiples of 3 line up vertically. (And the multiples of 6, with a factor of 2 and a factor of 3, do as well.)

But it’s also fun what happens to the color for Base Plus One and Base Minus One.

In the 10×10 chart, look at what happens to the color for 11, orange, and the multiples of 11. They go diagonally to the right up the chart: 11, 22, 33, 44, . . .

In the 10×10 chart, 9 is represented by two sections of blue, for 3 x 3. These colors go diagonally up the chart in the opposite direction: 9, 18, 27, 36, . . .

In the 8×8 chart, the octal number 11 is the decimal number 9 — so it is still represented by two sections of blue. But since 9 is one bigger than our base in that chart, the two sections of blue go diagonally up the chart to the right — just like 11 in the decimal chart.

In the octal chart, the color for 7, purple, goes diagonally up the chart to the left, with the octal numbers 7, 16, 25, 34, . . . .

In the 6×6 chart, we’ve got the same patterns, this time with 7 (which is 11 in base six) and 5.

7 (purple) goes diagonally right up the chart, and 5 goes diagonally left up the chart.

And we’ve got the same patterns in a 7×7 Base Seven chart:

Notice that since 7 is prime, no colors line up except purple, the color for 7.

And the colors for 8 and 6 go diagonally up the chart.

The Hexadecimal chart in base 16 is even more interesting:

Notice how all the multiples of 2 line up vertically, with multiples of 4, 8, and 16 also lined up.

11 in Base 16 is decimal 17, which is brown, and it acts like all the other 11s, going diagonally up and to the right.

1 less than 16 is F = 15, and the blue and green colors for F go diagonally up and to the left.

Before I finish I want to mention one more pattern I noticed from looking at these charts. It’s the familiar trick in Base 10 of the rule for figuring out if any number is a multiple of 9: Just add up the digits, and they will be a multiple of 9.

The reason this works is that 10 is congruent to 1 mod 9.
In base 10, each decimal place represents a number multiplied by a power of 10.
In base 9, that’s going to be the same as multiplying by 1 — so if you add up the digits, you get what the number is congruent to mod 9.

If none of that made any sense to you, just know this:
If you add up the digits of a base 10 number (and if you get a number bigger than 9, add them up again), your result is the remainder you’ll get if you divide the number by 9.

Since multiples of 9 have no remainder when divided by 9 — the digits of multiples of 9 in base 10 always add up to multiples of 9. (And by the same reasoning, the digits of multiples of 3 in base 10 always add up to multiples of 3.)

But you might have noticed when looking at the diagonal colors:

In Base 8, the digits of multiples of 7 always add up to multiples of 7.

In Base 6, the digits of multiples of 5 always add up to multiples of 5.

In Base 7, the digits of multiples of 6 always add up to multiples of 6.
And the digits of multiples of 2 always add up to multiples of 2.
And the digits of multiples of 3 always add up to multiples of 3.
(Use the colors to tell which numbers these are in Base 7.)

In Base 16, the digits of multiples of F (15) always add up to multiples of F.
And the digits of multiples of 5 always add up to multiples of 5.
And the digits of multiples of 3 always add up to multiples of 3.
(Use the colors to tell which numbers these are in Base 16.)

Forgive me, but I think these patterns are Awesome!

Let’s face it, you’ll see them much more clearly if you color the charts yourself!

Happy Coloring!

## Coloring to Learn Math Concepts!

I’m super excited about something I’ve been working on lately — posting Mathematical Coloring Sheets on my Sonderknitting webpage.

Why Sonderknitting? Because the ideas in the coloring pages come from my mathematical knitting projects, which all began with my Prime Factorization Sweater.

I wore the sweater to the library today, for our Family Math Games event. (We have lots of board games and card games that build math skills and ask only that parents play with their kids.) I also printed out some copies of the Prime Factorization Coloring Sheet — the one that matches my sweater — and brought some crayons.

A girl named Ana who is a regular at our Crazy 8s Math Club was there. She got tired of playing games with her little brother, and her Mom showed Ana the coloring sheet, and Ana became the first actual child to color one!

I explained the idea to Ana, using my sweater as a visual aid.

There are different ways you can approach it, but what I suggested was to choose a color for 2, then color a section of every second number. Then choose a color for 3 and color a section of every third number. Then I had to explain you use the color for 2 again to color a second section in the square for 4, then give every 4th number a second section of the color for 2. Then you choose a new color for 5, and she quickly caught on that all the multiples of 5 were in columns….

I can’t tell you how happy it made me to hear what she’d say as she was understanding how to do it (“Oh, I see!”) and seeing the patterns come out.

I think Ana’s in 2nd grade (Crazy 8s is for Kindergarten to 2nd grade.), so she can’t have studied much multiplication in school yet. So it made me all the happier to see the wheels turning and the connections forming.

But my favorite thing she said? “I like this! This is fun!”