Prime Factor Art on a Hundred Chart

The best way to practice math is to play with it — to use the patterns and connections between math concepts in your pursuit of something fun or beautiful.

So this art project is a great way to practice multiplication. Use the prime factors of numbers from one to one hundred to create a colorful design.

Start with a Hundred Chart

First, download this printable file of hundred charts in non-photo blue (or light gray, if you’re printing in grayscale). The file includes:

  • Line-by-line traditional chart, counting from top to bottom.
  • Line-by-line bottom’s-up chart, counting from bottom to top.
  • Ulam’s Spiral chart, spiraling out from the center.
  • Blank grids for making your own patterns.

Download the Printable Charts

Continue reading Prime Factor Art on a Hundred Chart

Kenken is Mathematical Play

It’s back-to-school time here in the States. And that means it’s time for the Kenken Classroom Newsletter. Yay for math puzzles!

KenKen arithmetic puzzles build mental math skills, logical reasoning, persistence, and mathematical confidence.

Free via email every Friday during the school year.

What a great way to prepare your children for success in math!

Sign up anytime:

Click Here for KenKen Classroom Newsletter

Continue reading Kenken is Mathematical Play

Math Game: Place Value Fish

Math Concepts: addition, subtraction, place value to six or seven digits.
Players: two or more.
Equipment: pencil and paper.

Set-Up

Each player needs a sheet of blank or lined paper, and a pencil.

At the top of your page, write a 6-digit number. All the digits must be different, and none of them can be zero.

How to Play

On your turn, you go fishing for points. Ask one other player, “Give me your _____’s.” The blank is for the single-digit number of your choice.

The other player answers, “You get _____.” This blank is for the value of that digit in the other player’s number.

For example, suppose you asked for 5’s. If the other player has a 5 in the tens place of his number, you get 50 points. But if 5 was in the ten-thousands place, you would get 50,000. And if there is no 5 at all, you get zero.

You add those points to your number. The other player subtracts the points from his number.

Then it’s the next player’s turn to go fishing.

Notice These Rules

Your number may change with each turn (except when you get zero). Always use your most recent number to add or subtract the fishing points.

If you have more than one of the digit asked for (like the player on the left above, who has two 7’s), you may choose which one to give away. That is, you can give the other player 70 points and not even mention the 7,000.

Endgame

Keep taking turns until every player gets five chances to fish for points. After five rounds, whoever has the highest score wins the game.

UNLESS the winner made an arithmetic error.

Be sure to check each other’s math, because any player who makes a mistake automatically loses the game.

Share the Fun

If you try this math game with your kids, I’d love to hear how it goes. Please drop a comment below.

And tell us about your favorite math game, so we can all play that, too. 😀

CREDITS: This game comes from Michael Schiro’s book Mega-Fun Math Games: 70 Quick-and-Easy Games to Build Math Skills. Feature photo (top) by Ruben Ortega via Unsplash.

A Puzzle for Palindromes

If you haven’t seen the meme going around, this is a palindrome week because the dates (written American style and with the year shortened to ’19) are the same when reversed.

Here’s a math puzzle for palindrome week — or any time you want to play with math:

  • Print a 100 chart.
  • Choose a color code.
  • Play!

What do you think: Will all numbers eventually turn into palindromes?

Links

You can find all sorts of hundred charts on my Free Math Printable Files page.

Read about the history of palindromes on Nrich Math’s Palindromes page.

Find out more about the Palindromic Number Conjecture in Mark Chubb’s article An Unsolved Problem your Students Should Attempt.

Or play with Manan Shah’s advanced palindromic number questions.

Get Your Weekly KenKen Puzzles for Kids

KenKen6x6

KenKen arithmetic puzzles build mental math skills, logical reasoning, persistence, and mathematical confidence.

Free via email every Friday during the school year.

What a great way to prepare your children for success in math!

Sign up anytime:

Click Here for KenKen Classroom Newsletter

How to Play

For easy printing, right-click to open the image above in a new tab.

Place the numbers from 1 to 6 into each row and column. None of the numbers may repeat in any row or column. Within the black “cages,” the numbers must add, subtract, multiply, or divide to give the answer shown.

Math Activity: Polite Numbers

Did you know that numbers can be polite? In math, a polite number is any number we can write as the sum of two or more consecutive positive whole numbers.

(Consecutive means numbers that come one right after another in the counting sequence.)

For example, five is a polite number, because we can write it as the sum of two consecutive numbers:
5 = 2 + 3

Nine is a doubly polite number, because we can write it two ways:
9 = 4 + 5
9 = 2 + 3 + 4

And fifteen is an amazingly polite number. We can write fifteen as the sum of consecutive numbers in three ways:
15 = 7 + 8
15 = 4 + 5 + 6
15 = 1 + 2 + 3 + 4 + 5

How many other polite numbers can you find?

You can build polite numbers (like fifteen) with a staircase of blocks.

What Do You Notice?

Are all numbers polite?

Or can you find an impolite number?

Can you make a collection of polite and impolite numbers? Find as many as you can.

How many different ways can you write each polite number as a sum of consecutive numbers?

What do you notice about your collection of polite and impolite numbers?

Can you think of a way to organize your collection so you can look for patterns?

What Do You Wonder?

Make a conjecture about polite or impolite numbers. A conjecture is a statement that you think might be true.

For example, you might make a conjecture that “All odd numbers are…” — How would you finish that sentence?

Make another conjecture.

And another.

Can you make at least five conjectures about polite and impolite numbers?

What is your favorite conjecture? Does thinking about it make you wonder about numbers?

Can you think of any way to test your conjectures, to know whether they will always be true or not?

Real Life Math Is Social

This is how mathematics works. Mathematicians play with numbers, shapes, or ideas and explore how those relate to other ideas.

After collecting a set of interesting things, they think about ways to organize them, so they can look for patterns and connections. They make conjectures and try to imagine ways to test them.

And mathematicians compare their ideas with each other. In real life, math is a very social game.

So play with polite and impolite numbers. Compare your conjectures with a friend.

Share your ideas in the comments section below.

And check out the list of student conjectures at the Ramblings of a Math Mom blog.

CREDITS: Numbers photo (top) by James Cridland via Flickr (CC BY 2.0). I first saw this activity at Dave Marain’s Math Notations blog, and it’s also available as a cute printable Nrich poster. For a detailed analysis, check out Wai Yan Pong’s “Sums of Consecutive Integers” article.

Math Game: Six Hundred

Today I’m working on the next book in my Math You Can Play series, culling the games that don’t fit. Six Hundred is a fine game, but I can’t figure out how it landed in the prealgebra manuscript…

Math Concepts: addition, multiplication, parity (odd or even).
Players: any number.
Equipment: six regular 6-sided dice (my math club kids love this set), free printable score sheet, pen or pencil.

Click Here for the Score Sheet

Set-Up

A full game consists of eighteen rounds of play. Players may share the dice and score sheet, taking turns around the table. But for a large group you may want to have extras, so that two or more people can be rolling their dice at the same time.

How to Play

On your turn, roll all six dice up to three times. After each roll, you may set aside one or more dice to keep for scoring, if you wish. Once a die has been set aside, you may not change your mind and roll it again.

After the third roll, choose an unused category on your score sheet. Count the dice according to the rules for that section, and write down your score. If your dice do not fit anywhere, then you must take a zero in the category of your choice.

When all players have filled their score sheet and recorded any appropriate bonuses (or penalties), whoever has the highest score wins.

Scoring

Dice are scored in eighteen categories, in four sections, as follows. The maximum possible score is 600 points.

Numbers

Record the sum of only the dice showing that number. For example, if you rolled 1, 1, 3, 4, 4, 4, you could score 2 in the Ones category. Or you could score 12 in the Fours category, or zero in the Fives.

Bonus: If the combined Numbers score is 80 or more, add 35 points to your total.

Rungs (1–4)

Score the total of all six dice. Like a ladder, the score in each rung must be greater than the one before it. Rung 1 gets the lowest number, and Rung 4 the highest.

You may fill in the rungs in any order. But if you write 18 in Rung 2, then the score in Rung 1 must be 17 or less, and the score in Rung 3 must be at least 19.

Penalty: If the Rung scores don’t fit the ascending value rule, this category is worth zero.

Clusters

Score the total of all six dice, if they fit the rules for that category.

  • Four of a Kind: at least four dice show the same number.
  • Five of a Kind: at least five dice show the same number.
  • Odds: all six dice show odd numbers.
  • Evens: all six dice show even numbers.
Patterns

Score the amount shown for each pattern.

  • Series: 30 points you roll 1, 2, 3, 4, 5, 6.
  • Pairs: 30 points if you roll three pairs of matching numbers. Four dice showing the same number may be counted as two pairs.
  • Triplets: 30 points if you roll two sets of three dice with the same numbers, such as three 2s and three 5s.
  • Sextet: 36 points when all six dice show the same number.
Game Bonus

If you score at least one point in all eighteen categories, or if the only zero you take is for the sextet, then award yourself an additional 36 points.

History

Players around the world have played poker-style dice games for ages. I grew up with Yahtzee, but you may know the game by Yatzy, Yacht, Generala, or another name.

Reiner Knizia included this mathematical version in his book Dice Games Properly Explained. And I found it online at Michael Ayers’s Stick Insect blog.

John Golden posted a simpler “Mathzee” game played with five dice on his Math Hombre blog — and while you’re there, be sure to check out his amazing Math Games page.

CREDITS: Feature photo (top) by rekre89 via Flickr (CC BY 2.0).

2019 Mathematics Game: Playful Math for All Ages

Happy 2019! Have you set any goals for the year?

My goals are to continue playing with math (1) in my homeschool coop classes and (2) on this blog — and (3) hopefully to publish a couple of new books as well.

My favorite way to celebrate any new year is by playing the Year Game. It’s a prime opportunity for players of all ages to fulfill the two most popular New Year’s Resolutions: spending more time with family and friends, and getting more exercise.

So grab a partner, slip into your workout clothes, and pump up those mental muscles!

Rules of the Game

Use the digits in the year 2019 to write mathematical expressions for the counting numbers 1 through 100. The goal is adjustable: Young children can start with looking for 1-10, middle grades with 1-25.

  • You must use all four digits. You may not use any other numbers.
  • Solutions that keep the year digits in 2-0-1-9 order are preferred, but not required.
  • You may use a decimal point to create numbers such as .2, .02, etc., but you cannot write 0.02 because we only have one zero in this year’s number.
  • You may create multi-digit numbers such as 10 or 201 or .01, but we prefer solutions that avoid them.

My Special Variations on the Rules

  • You MAY use the overhead-bar (vinculum), dots, or brackets to mark a repeating decimal. But students and teachers beware: you can’t submit answers with repeating decimals to Math Forum.
  • You may NOT use a double factorial, n!! = the product of all integers from 1 to n that have the same parity (odd or even) as n. The Math Forum allows them, but I feel much more creative when I can wrangle a solution without invoking them.

For many years mathematicians, scientists, engineers and others interested in mathematics have played “year games” via e-mail and in newsgroups. We don’t always know whether it is possible to write expressions for all the numbers from 1 to 100 using only the digits in the current year, but it is fun to try to see how many you can find.

Math Forum Year Game Site

Click here to continue reading.

Mathematics Is Worthy

“When I began my college education, I still had many doubts about whether I was good enough for mathematics. Then a colleague said the decisive words to me: it is not that I am worthy to occupy myself with mathematics, but rather that mathematics is worthy for one to occupy oneself with.”

Rózsa Péter
Mathematics is beautiful
essay in The Mathematical Intelligencer

Rózsa Péter and the Curious Students

I would like to win over those who consider mathematics useful, but colourless and dry — a necessary evil…
 
No other field can offer, to such an extent as mathematics, the joy of discovery, which is perhaps the greatest human joy.
 
The schoolchildren that I have taught in the past were always attuned to this, and so I have also learned much from them.
 
It never would have occurred to me, for instance, to talk about the Euclidean Algorithm in a class with twelve-year-old girls, but my students led me to do it.
 
I would like to recount this lesson.
 
What we were busy with was that I would name two numbers, and the students would figure out their greatest common divisor. For small numbers this went quickly. Gradually, I named larger and larger numbers so that the students would experience difficulty and would want to have a procedure.
 
I thought that the procedure would be factorization into primes.
 
They had still easily figured out the greatest common divisor of 60 and 48: “Twelve!”
 
But a girl remarked: “Well, that’s just the same as the difference of 60 and 48.”
 

 
“That’s a coincidence,” I said and wanted to go on.
 
But they would not let me go on: “Please name us numbers where it isn’t like that.”
 
“Fine. 60 and 36 also have 12 as their greatest common divisor, and their difference is 24.”
 

 
Another interruption: “Here the difference is twice as big as the greatest common divisor.”
 
“All right, if this will satisfy all of you, it is in fact no coincidence: the difference of two numbers is always divisible by all their common divisors. And so is their sum.”
 
Certainly that needed to be stated in full, but having done so, I really did want to move on.
 
However, I still could not do that.
 
A girl asked: “Couldn’t they discover a procedure to find the greatest common divisor just from that?”
 

 
They certainly could! But that is precisely the basic idea behind the Euclidean Algorithm!
 
So I abandoned my plan and went the way that my students led me.
 

— Rózsa Péter
quoted at the MacTutor History of Mathematics Archive

For Further Exploration

Note: When the video narrator says “Greatest Common Denominator,” he really means “Greatest Common Divisor.”

CREDITS: “Pink toned thoughts on a hike” photo courtesy of Simon Matzinger on Unsplash.

FAQ: Struggling with Arithmetic

My son can’t stand long division or fractions. We had a lesson on geometry, and he enjoyed that — especially the 3-D shapes. If we can just get past the basics, then we’ll have time for the things he finds interesting. But one workbook page takes so long, and I’m sick of the drama. Should we keep pushing through?

Those upper-elementary arithmetic topics are important. Foundational concepts. Your son needs to master them.

Eventually.

But the daily slog through page after page of workbook arithmetic can wear anyone down.

Many children find it easier to focus on math when it’s built into a game.

Take a look at Colleen King’s Math Playground website. Or try one of the ideas on John Golden’s Math Hombre Games blog page.

Or sometimes a story helps, like my Cookie Factory Guide to Long Division.

Math Textbook Tips

Games are great for practicing math your child has already learned. But for introducing new concepts, you’ll probably want to follow your textbook.

Still, even with textbook math, there are ways to make the journey less tedious:

  • Most children do not need to do every problem on a workbook page, or every page in a section. There is a lot of extra review built into any math program.
     
  • You don’t have to finish a section before you work whatever comes after it. Use sticky bookmarks to keep track of your position in two or three chapters at a time. Do a little bit of the mundane arithmetic practice, and then balance that with some of the more interesting topics your son enjoys.
     
  • As much as possible, do math out loud with a whiteboard for scratch work. Somehow, working with colorful markers makes arithmetic more bearable.
     
  • Set a timer for math, and make the time short enough that he feels the end is in sight. I suggest no more than thirty minutes a day for now. And whenever the timer rings, stop immediately — even if you are in the middle of a problem.
     

The Timer Can Be a Life-Saver

Doing math in short sessions helped us avoid the emotional melt-downs my daughter used to have.

Thinking is hard work, and if I asked for too much, she would crash.

Because I sat with her and worked together every problem, I knew what she understood and when we could skip a problem. Or sometimes even jump several pages. Which meant that, even with short lessons, we still got through our book on time.

Arithmetic Is Like Vegetables

But as I said before, textbooks include a whole lot of repetition.

Too much repetition deadens the brain.

So we also took long breaks from our textbook program. Entire school-year-long breaks, just playing with math. Letting “enrichment” activities be our whole curriculum.

As healthy as vegetables are, you would never limit your son to eating just lima beans and corn.

Similarly, be sure to feed him a varied math diet.

For example, you can follow his interest in geometry beyond the standard school topics.

Explore tessellations, Escher art, and impossible shapes such as the Penrose triangle.

Building Lego scenes is a practical application of 3-D geometry. He might even want to try stop motion animation.

Talk about how math works in real life. Ponder the choices on John Stevens’s “Would You Rather?” blog or try some of the challenges at Andrew Stadel’s Estimation 180 website. Many of these require three-dimensional reasoning.

How is the Penrose triangle illusion created? Why can’t we build one in the real world?

Click for details about Let's Play Math bookThis post is an excerpt from my book Let’s Play Math: How Families Can Learn Math Together—and Enjoy It, as are many of the articles in my Let’s Play Math FAQ series.

CREDITS: Frustrated Child photo by by Pixabay on Pexels.com. Penrose Lego by Erik Johansson via Flickr (CC BY 2.0). Homework Hands photo by Tamarcus Brown on Unsplash.